diff --git a/application/Espo/Core/Api/Auth.php b/application/Espo/Core/Api/Auth.php
index 939b5b2ddc..2776eaff52 100644
--- a/application/Espo/Core/Api/Auth.php
+++ b/application/Espo/Core/Api/Auth.php
@@ -67,7 +67,7 @@ class Auth
         $this->authRequired = $authRequired;
     }
 
-    public function createForEntryPoint(Authentication $authentication, bool $authRequired = true)
+    public static function createForEntryPoint(Authentication $authentication, bool $authRequired = true)
     {
         $instance = new Auth($authentication, $authRequired);
         $instance->isEntryPoint = true;
diff --git a/application/Espo/Core/Cleanup/Reminders.php b/application/Espo/Core/Cleanup/Reminders.php
index 358c0a0bd7..5eeccdbc84 100644
--- a/application/Espo/Core/Cleanup/Reminders.php
+++ b/application/Espo/Core/Cleanup/Reminders.php
@@ -54,15 +54,14 @@ class Reminders
         $dt = new \DateTime();
         $dt->modify($period);
 
-        $pdo = $this->entityManager->getPDO();
+        $delete = $this->entityManager->getQueryBuilder()
+            ->delete()
+            ->from('Reminder')
+            ->where([
+                'remindAt<' => $dt->format('Y-m-d'),
+            ])
+            ->build();
 
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Reminder', [
-            'whereClause' => [
-                'remindAt<' => $dt->format('Y-m-d')
-            ],
-        ]);
-
-        $sth = $pdo->prepare($sql);
-        $sth->execute();
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 }
diff --git a/application/Espo/Core/Formula/Functions/EntityGroup/SumRelatedType.php b/application/Espo/Core/Formula/Functions/EntityGroup/SumRelatedType.php
index 7673c51feb..167a6211c5 100644
--- a/application/Espo/Core/Formula/Functions/EntityGroup/SumRelatedType.php
+++ b/application/Espo/Core/Formula/Functions/EntityGroup/SumRelatedType.php
@@ -134,7 +134,7 @@ class SumRelatedType extends \Espo\Core\Formula\Functions\Base implements
 
         $entityManager->getRepository($foreignEntityType)->handleSelectParams($selectParams);
 
-        $sql = $entityManager->getQuery()->createSelectQuery($foreignEntityType, $selectParams);
+        $sql = $entityManager->getQueryComposer()->createSelectQuery($foreignEntityType, $selectParams);
 
         $pdo = $entityManager->getPDO();
         $sth = $pdo->prepare($sql);
diff --git a/application/Espo/Core/ORM/Repository/HookMediator.php b/application/Espo/Core/ORM/Repository/HookMediator.php
new file mode 100644
index 0000000000..53b6322ba8
--- /dev/null
+++ b/application/Espo/Core/ORM/Repository/HookMediator.php
@@ -0,0 +1,98 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\ORM\Repository;
+
+use Espo\ORM\{
+    Entity,
+    Repository\EmptyHookMediator,
+    QueryParams\Select,
+};
+
+use Espo\Core\HookManager;
+
+class HookMediator extends EmptyHookMediator
+{
+    protected $hookManager;
+
+    public function __construct(HookManager $hookManager)
+    {
+        $this->hookManager = $hookManager;
+    }
+
+    public function afterRelate(Entity $entity, string $relationName, Entity $foreignEntity, ?array $columnData, array $options)
+    {
+        if (!empty($options['skipHooks'])) {
+            return;
+        }
+
+        $hookData = [
+            'relationName' => $relationName,
+            'relationData' => $columnData,
+            'foreignEntity' => $foreignEntity,
+            'foreignId' => $foreignEntity->id,
+        ];
+
+        $this->hookManager->process(
+            $entity->getEntityType(), 'afterRelate', $entity, $options, $hookData
+        );
+    }
+    public function afterUnrelate(Entity $entity, string $relationName, Entity $foreignEntity, array $options)
+    {
+        if (!empty($options['skipHooks'])) {
+            return;
+        }
+
+        $hookData = [
+            'relationName' => $relationName,
+            'foreignEntity' => $foreignEntity,
+            'foreignId' => $foreignEntity->id,
+        ];
+
+        $this->hookManager->process(
+            $entity->getEntityType(), 'afterUnrelate', $entity, $options, $hookData
+        );
+    }
+
+    public function afterMassRelate(Entity $entity, string $relationName, Select $query, array $options)
+    {
+        if (!empty($options['skipHooks'])) {
+            return;
+        }
+
+        $hookData = [
+            'relationName' => $relationName,
+            'query' => $query,
+        ];
+
+        $this->hookManager->process(
+            $entity->getEntityType(), 'afterMassRelate', $entity, $options, $hookData
+        );
+    }
+}
diff --git a/application/Espo/Core/ORM/RepositoryFactory.php b/application/Espo/Core/ORM/RepositoryFactory.php
index f00d6fae9d..34f69ada30 100644
--- a/application/Espo/Core/ORM/RepositoryFactory.php
+++ b/application/Espo/Core/ORM/RepositoryFactory.php
@@ -35,7 +35,10 @@ use Espo\Core\{
     Repositories\Database as DatabaseRepository,
 };
 
-use Espo\ORM\RepositoryFactory as RepositoryFactoryInterface;
+use Espo\ORM\{
+    Repository\RepositoryFactory as RepositoryFactoryInterface,
+    Repository\Repository,
+};
 
 class RepositoryFactory implements RepositoryFactoryInterface
 {
@@ -58,7 +61,7 @@ class RepositoryFactory implements RepositoryFactoryInterface
         return $this->classFinder->find('Repositories', $name);
     }
 
-    public function create(string $name) : object
+    public function create(string $name) : Repository
     {
         $className = $this->getClassName($name);
 
diff --git a/application/Espo/Core/Repositories/CategoryTree.php b/application/Espo/Core/Repositories/CategoryTree.php
index 50bb4f4c65..08f4fad067 100644
--- a/application/Espo/Core/Repositories/CategoryTree.php
+++ b/application/Espo/Core/Repositories/CategoryTree.php
@@ -38,7 +38,7 @@ class CategoryTree extends Database
 		parent::afterSave($entity, $options);
 
 		$pdo = $this->getEntityManager()->getPDO();
-		$query = $this->getEntityManager()->getQuery();
+		$query = $this->getEntityManager()->getQueryComposer();
 
 		$parentId = $entity->get('parentId');
 		$pathsTableName = $query->toDb($query->sanitize($entity->getEntityType()) . 'Path');
@@ -91,7 +91,7 @@ class CategoryTree extends Database
 		parent::afterRemove($entity, $options);
 
 		$pdo = $this->getEntityManager()->getPDO();
-		$query = $this->getEntityManager()->getQuery();
+		$query = $this->getEntityManager()->getQueryComposer();
 
 		$pathsTableName = $query->toDb($query->sanitize($entity->getEntityType()) . 'Path');
 
diff --git a/application/Espo/Core/Repositories/Database.php b/application/Espo/Core/Repositories/Database.php
index 8f4782d736..3d6d4ae40d 100644
--- a/application/Espo/Core/Repositories/Database.php
+++ b/application/Espo/Core/Repositories/Database.php
@@ -30,13 +30,14 @@
 namespace Espo\Core\Repositories;
 
 use Espo\ORM\{
-    Repositories\RDB,
+    Repository\RDBRepository,
     Entity,
 };
 
 use Espo\Core\ORM\{
     EntityManager,
     EntityFactory,
+    Repository\HookMediator,
 };
 
 use Espo\Core\{
@@ -46,7 +47,7 @@ use Espo\Core\{
     ApplicationState,
 };
 
-class Database extends RDB
+class Database extends RDBRepository
 {
     protected $hooksDisabled = false;
 
@@ -72,7 +73,13 @@ class Database extends RDB
         $this->hookManager = $hookManager;
         $this->applicationState = $applicationState;
 
-        parent::__construct($entityType, $entityManager, $entityFactory, $metadata);
+        $hookMediator = null;
+
+        if (!$this->hooksDisabled) {
+            $hookMediator = new HookMediator($hookManager);
+        }
+
+        parent::__construct($entityType, $entityManager, $entityFactory, $hookMediator);
     }
 
     protected function getMetadata()
@@ -178,8 +185,7 @@ class Database extends RDB
 
     public function remove(Entity $entity, array $options = [])
     {
-        $result = parent::remove($entity, $options);
-        return $result;
+        return parent::remove($entity, $options);
     }
 
     protected function afterRelate(Entity $entity, $relationName, $foreign, $data = null, array $options = [])
@@ -198,15 +204,7 @@ class Database extends RDB
             }
 
             if ($foreign instanceof Entity) {
-                $hookData = [
-                    'relationName' => $relationName,
-                    'relationData' => $data,
-                    'foreignEntity' => $foreign,
-                    'foreignId' => $foreign->id,
-                ];
-                $this->hookManager->process(
-                    $this->entityType, 'afterRelate', $entity, $options, $hookData
-                );
+                $this->hookMediator->afterRelate($entity, $relationName, $foreign, $data, $options);
             }
         }
     }
@@ -227,14 +225,7 @@ class Database extends RDB
             }
 
             if ($foreign instanceof Entity) {
-                $hookData = [
-                    'relationName' => $relationName,
-                    'foreignEntity' => $foreign,
-                    'foreignId' => $foreign->id,
-                ];
-                $this->hookManager->process(
-                    $this->entityType, 'afterUnrelate', $entity, $options, $hookData
-                );
+                $this->hookMediator->afterUnrelate($entity, $relationName, $foreign, $options);
             }
         }
     }
diff --git a/application/Espo/Core/Repositories/Event.php b/application/Espo/Core/Repositories/Event.php
index aa68561b50..f4664d48a2 100644
--- a/application/Espo/Core/Repositories/Event.php
+++ b/application/Espo/Core/Repositories/Event.php
@@ -34,7 +34,7 @@ use Espo\Core\Utils\Util;
 
 use Espo\Core\Di;
 
-class Event extends \Espo\Core\Repositories\Database implements
+class Event extends Database implements
     Di\DateTimeAware,
     Di\ConfigAware
 {
@@ -125,16 +125,16 @@ class Event extends \Espo\Core\Repositories\Database implements
     {
         parent::afterRemove($entity, $options);
 
-        $pdo = $this->getEntityManager()->getPDO();
-
-        $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('Reminder', [
-            'whereClause' => [
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
+            ->from('Reminder')
+            ->where([
                 'entityId' => $entity->id,
                 'entityType' => $entity->getEntityType(),
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
     }
 
     protected function afterSave(Entity $entity, array $options = [])
diff --git a/application/Espo/Core/Select/SelectManager.php b/application/Espo/Core/Select/SelectManager.php
index a395b9d4d5..9063ed6224 100644
--- a/application/Espo/Core/Select/SelectManager.php
+++ b/application/Espo/Core/Select/SelectManager.php
@@ -44,7 +44,7 @@ use Espo\Core\{
     ORM\EntityManager,
 };
 
-use Espo\ORM\DB\Query\BaseQuery as Query;
+use Espo\ORM\QueryComposer\BaseQueryComposer as QueryComposer;
 
 use Espo\ORM\Entity;
 
@@ -373,19 +373,23 @@ class SelectManager
                 $key = $midKeys[1];
                 $part[$link . 'Filter' . 'Middle.' . $key] = $idsValue;
             }
+
         } else if ($relationType == 'hasMany') {
             $alias = $link . 'Filter';
             $this->addLeftJoin([$link, $alias], $result);
 
             $part[$alias . '.id'] = $idsValue;
+
         } else if ($relationType == 'belongsTo') {
             $key = $seed->getRelationParam($link, 'key');
             if (!empty($key)) {
                 $part[$key] = $idsValue;
             }
+
         } else if ($relationType == 'hasOne') {
             $this->addJoin([$link, $link . 'Filter'], $result);
             $part[$link . 'Filter' . '.id'] = $idsValue;
+
         } else {
             return;
         }
@@ -403,7 +407,7 @@ class SelectManager
             $idsValue = $idsValue[0];
         }
 
-        $query = $this->getEntityManager()->getQuery();
+        $query = $this->getEntityManager()->getQueryComposer();
 
         $seed = $this->getSeed();
 
@@ -441,7 +445,7 @@ class SelectManager
     {
         $relDefs = $this->getSeed()->getRelations();
 
-        $query = $this->getEntityManager()->getQuery();
+        $query = $this->getEntityManager()->getQueryComposer();
 
         $tableName = $query->toDb($this->getSeed()->getEntityType());
 
@@ -542,6 +546,9 @@ class SelectManager
         if (empty($result)) {
             $result = [];
         }
+        if (empty($result['from'])) {
+            $result['from'] = $this->entityType;
+        }
         if (empty($result['joins'])) {
             $result['joins'] = [];
         }
@@ -980,7 +987,7 @@ class SelectManager
             }
 
             if ($attribute && $checkWherePermission) {
-                $argumentList = Query::getAllAttributesFromComplexExpression($attribute);
+                $argumentList = QueryComposer::getAllAttributesFromComplexExpression($attribute);
                 foreach ($argumentList as $argument) {
                     $this->checkWhereArgument($argument, $type);
                 }
@@ -1770,21 +1777,26 @@ class SelectManager
                         $key = $midKeys[1];
                         $part[$alias . 'Middle.' . $key] = $value;
                     }
+
                 } else if ($relationType == 'hasMany') {
                     $this->addLeftJoin([$link, $alias], $result);
 
                     $part[$alias . '.id'] = $value;
+
                 } else if ($relationType == 'belongsTo') {
                     $key = $seed->getRelationParam($link, 'key');
                     if (!empty($key)) {
                         $part[$key] = $value;
                     }
+
                 } else if ($relationType == 'hasOne') {
                     $this->addLeftJoin([$link, $alias], $result);
                     $part[$alias . '.id'] = $value;
+
                 } else {
                     break;;
                 }
+
                 $this->setDistinct(true, $result);
                 break;
 
@@ -1800,30 +1812,45 @@ class SelectManager
                 $alias = $link . 'NotLinkedFilter' . strval(rand(10000, 99999));
 
                 if ($relationType == 'manyMany') {
-                    $this->addLeftJoin([$link, $alias], $result);
-                    $midKeys = $seed->getRelationParam($link, 'midKeys');
+                    $key = $seed->getRelationParam($link, 'midKeys')[1];
+
+                    $this->addLeftJoin(
+                        [
+                            $link, $alias, [$key => $value],
+                        ],
+                        $result
+                    );
+
+                    $part[$alias . 'Middle.' . $key] = null;
 
-                    if (!empty($midKeys)) {
-                        $key = $midKeys[1];
-                        $result['joinConditions'][$alias] = [$key => $value];
-                        $part[$alias . 'Middle.' . $key] = null;
-                    }
                 } else if ($relationType == 'hasMany') {
-                    $this->addLeftJoin([$link, $alias], $result);
-                    $result['joinConditions'][$alias] = ['id' => $value];
+                    $this->addLeftJoin(
+                        [
+                            $link, $alias, ['id' => $value]
+                        ],
+                        $result
+                    );
+
                     $part[$alias . '.id'] = null;
+
                 } else if ($relationType == 'belongsTo') {
                     $key = $seed->getRelationParam($link, 'key');
+
                     if (!empty($key)) {
                         $part[$key . '!='] = $value;
                     }
+
                 } else if ($relationType == 'hasOne') {
                     $this->addLeftJoin([$link, $alias], $result);
+
                     $part[$alias . '.id!='] = $value;
+
                 } else {
                     break;
                 }
+
                 $this->setDistinct(true, $result);
+
                 break;
 
             case 'arrayAnyOf':
@@ -2320,7 +2347,7 @@ class SelectManager
             }
 
             $fullTextSearchColumnSanitizedList = [];
-            $query = $this->getEntityManager()->getQuery();
+            $query = $this->getEntityManager()->getQueryComposer();
             foreach ($fullTextSearchColumnList as $i => $field) {
                 $fullTextSearchColumnSanitizedList[$i] = $query->sanitize($query->toDb($field));
             }
@@ -2744,7 +2771,7 @@ class SelectManager
     protected function applyLeftJoinsFromAttribute(string $attribute, array &$result)
     {
         if (strpos($attribute, ':') !== false) {
-            $argumentList = Query::getAllAttributesFromComplexExpression($attribute);
+            $argumentList = QueryComposer::getAllAttributesFromComplexExpression($attribute);
             foreach ($argumentList as $argument) {
                 $this->applyLeftJoinsFromAttribute($argument, $result);
             }
diff --git a/application/Espo/Core/Utils/Cron/Job.php b/application/Espo/Core/Utils/Cron/Job.php
index b2092673de..2c5547a8e1 100644
--- a/application/Espo/Core/Utils/Cron/Job.php
+++ b/application/Espo/Core/Utils/Cron/Job.php
@@ -307,8 +307,6 @@ class Job
      */
     public function removePendingJobDuplicates()
     {
-        $pdo = $this->getEntityManager()->getPDO();
-
         $duplicateJobList = $this->getEntityManager()->getRepository('Job')
             ->select(['scheduledJobId'])
             ->where([
@@ -352,14 +350,15 @@ class Job
                 continue;
             }
 
-            $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('Job', [
-                'whereClause' => [
+            $delete = $this->entityManager->getQueryBuilder()
+                ->delete()
+                ->from('Job')
+                ->where([
                     'id' => $jobIdList,
-                ]
-            ]);
+                ])
+                ->build();
 
-            $sth = $pdo->prepare($sql);
-            $sth->execute();
+            $this->entityManager->getQueryExecutor()->run($delete);
         }
     }
 
diff --git a/application/Espo/Core/Utils/Database/Schema/rebuildActions/Currency.php b/application/Espo/Core/Utils/Database/Schema/rebuildActions/Currency.php
index c422aae180..99a5852d08 100644
--- a/application/Espo/Core/Utils/Database/Schema/rebuildActions/Currency.php
+++ b/application/Espo/Core/Utils/Database/Schema/rebuildActions/Currency.php
@@ -31,7 +31,6 @@ namespace Espo\Core\Utils\Database\Schema\rebuildActions;
 
 class Currency extends \Espo\Core\Utils\Database\Schema\BaseRebuildActions
 {
-
     public function afterRebuild()
     {
         $defaultCurrency = $this->getConfig()->get('defaultCurrency');
@@ -39,16 +38,18 @@ class Currency extends \Espo\Core\Utils\Database\Schema\BaseRebuildActions
         $baseCurrency = $this->getConfig()->get('baseCurrency');
         $currencyRates = $this->getConfig()->get('currencyRates');
 
-        if ($defaultCurrency != $baseCurrency) {
+        if ($defaultCurrency !== $baseCurrency) {
             $currencyRates = $this->exchangeRates($baseCurrency, $defaultCurrency, $currencyRates);
         }
 
         $currencyRates[$defaultCurrency] = '1.00';
 
-        $pdo = $this->getEntityManager()->getPDO();
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
+            ->from('Currency')
+            ->build();
 
-        $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('Currency');
-        $pdo->prepare($sql)->execute();
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
 
         foreach ($currencyRates as $currencyName => $rate) {
             $this->getEntityManager()->createEntity('Currency', [
@@ -58,20 +59,12 @@ class Currency extends \Espo\Core\Utils\Database\Schema\BaseRebuildActions
         }
     }
 
-    /**
-     * Calculate exchange rates if defaultCurrency doesn't equals baseCurrency
-     *
-     * @param  string $baseCurrency
-     * @param  string $defaultCurrency
-     * @param  array $currencyRates   [description]
-     * @return array  - List of new currency rates
-     */
-    protected function exchangeRates($baseCurrency, $defaultCurrency, array $currencyRates)
+    protected function exchangeRates(string $baseCurrency, string $defaultCurrency, array $currencyRates) : array
     {
         $precision = 5;
         $defaultCurrencyRate = round(1 / $currencyRates[$defaultCurrency], $precision);
 
-        $exchangedRates = array();
+        $exchangedRates = [];
         $exchangedRates[$baseCurrency] = $defaultCurrencyRate;
 
         unset($currencyRates[$baseCurrency], $currencyRates[$defaultCurrency]);
@@ -82,6 +75,4 @@ class Currency extends \Espo\Core\Utils\Database\Schema\BaseRebuildActions
 
         return $exchangedRates;
     }
-
 }
-
diff --git a/application/Espo/Core/Utils/EntityManager.php b/application/Espo/Core/Utils/EntityManager.php
index 74a59e4c03..36ea0d3bb3 100644
--- a/application/Espo/Core/Utils/EntityManager.php
+++ b/application/Espo/Core/Utils/EntityManager.php
@@ -353,7 +353,11 @@ class EntityManager
         $entityDefsDataContents = $this->getFileManager()->getContents($filePath);
         $entityDefsDataContents = str_replace('{entityType}', $name, $entityDefsDataContents);
         $entityDefsDataContents = str_replace('{entityTypeLowerFirst}', lcfirst($name), $entityDefsDataContents);
-        $entityDefsDataContents = str_replace('{tableName}', $this->getEntityManager()->getQuery()->toDb($name), $entityDefsDataContents);
+        $entityDefsDataContents = str_replace(
+            '{tableName}',
+            $this->getEntityManager()->getQueryComposer()->toDb($name),
+            $entityDefsDataContents
+        );
         foreach ($replaceData as $key => $value) {
             $entityDefsDataContents = str_replace('{'.$key.'}', $value, $entityDefsDataContents);
         }
diff --git a/application/Espo/Core/Utils/Util.php b/application/Espo/Core/Utils/Util.php
index f610b4cc05..ca979ff94d 100644
--- a/application/Espo/Core/Utils/Util.php
+++ b/application/Espo/Core/Utils/Util.php
@@ -29,8 +29,6 @@
 
 namespace Espo\Core\Utils;
 
-use \Espo\Core\Exceptions\Error;
-
 class Util
 {
     /**
diff --git a/application/Espo/Hooks/Common/Notifications.php b/application/Espo/Hooks/Common/Notifications.php
index f8e73d8002..89ee170ffe 100644
--- a/application/Espo/Hooks/Common/Notifications.php
+++ b/application/Espo/Hooks/Common/Notifications.php
@@ -139,7 +139,7 @@ class Notifications
 
     public function afterRemove(Entity $entity)
     {
-        $query = $this->entityManager->getQuery();
+        $query = $this->entityManager->getQueryComposer();
         $sql = "
             DELETE FROM `notification`
             WHERE
diff --git a/application/Espo/Hooks/Common/Stream.php b/application/Espo/Hooks/Common/Stream.php
index 4c181df68b..e58eaeaf23 100644
--- a/application/Espo/Hooks/Common/Stream.php
+++ b/application/Espo/Hooks/Common/Stream.php
@@ -102,7 +102,7 @@ class Stream
             $this->getStreamService()->unfollowAllUsersFromEntity($entity);
         }
 
-        $query = $this->entityManager->getQuery();
+        $query = $this->entityManager->getQueryComposer();
         $sql = "
             UPDATE `note`
             SET `deleted` = 1, `modified_at` = '".date('Y-m-d H:i:s')."'
diff --git a/application/Espo/Jobs/Cleanup.php b/application/Espo/Jobs/Cleanup.php
index 47c6218d4f..d8f22ab9cf 100644
--- a/application/Espo/Jobs/Cleanup.php
+++ b/application/Espo/Jobs/Cleanup.php
@@ -118,7 +118,7 @@ class Cleanup implements Job
 
     protected function cleanupJobs()
     {
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('Job')
             ->where([
                 'DATE:modifiedAt<' => $this->getCleanupJobFromDate(),
@@ -126,9 +126,9 @@ class Cleanup implements Job
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
 
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('Job')
             ->where([
                 'DATE:modifiedAt<' => $this->getCleanupJobFromDate(),
@@ -137,12 +137,12 @@ class Cleanup implements Job
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupUniqueIds()
     {
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('UniqueId')
             ->where([
                 'terminateAt!=' => null,
@@ -150,7 +150,7 @@ class Cleanup implements Job
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupScheduledJobLog()
@@ -180,7 +180,7 @@ class Cleanup implements Job
                 $ignoreIdList[] = $logRecord->get('id');
             }
 
-            $select = $this->entityManager->createSelectBuilder()
+            $delete = $this->entityManager->getQueryBuilder()->delete()
                 ->from('ScheduledJobLogRecord')
                 ->where([
                     'scheduledJobId' => $scheduledJobId,
@@ -189,7 +189,7 @@ class Cleanup implements Job
                 ])
                 ->build();
 
-            $this->entityManager->getQueryExecutor()->delete($select);
+            $this->entityManager->getQueryExecutor()->run($delete);
         }
     }
 
@@ -199,14 +199,14 @@ class Cleanup implements Job
         $datetime = new \DateTime();
         $datetime->modify($period);
 
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('ActionHistoryRecord')
             ->where([
                 'DATE:createdAt<' => $datetime->format('Y-m-d'),
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupAuthToken()
@@ -215,7 +215,7 @@ class Cleanup implements Job
         $datetime = new \DateTime();
         $datetime->modify($period);
 
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('AuthToken')
             ->where([
                 'DATE:modifiedAt<' => $datetime->format('Y-m-d'),
@@ -223,7 +223,7 @@ class Cleanup implements Job
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupAuthLog()
@@ -232,14 +232,14 @@ class Cleanup implements Job
         $datetime = new \DateTime();
         $datetime->modify($period);
 
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('AuthLogRecord')
             ->where([
                 'DATE:createdAt<' => $datetime->format('Y-m-d'),
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function getCleanupJobFromDate()
@@ -348,7 +348,7 @@ class Cleanup implements Job
             }
         }
 
-        $select = $this->entityManager->createSelectBuilder()
+        $delete = $this->entityManager->getQueryBuilder()->delete()
             ->from('Attachment')
             ->where([
                 'deleted' => true,
@@ -356,7 +356,7 @@ class Cleanup implements Job
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->delete($select);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupEmails()
@@ -383,7 +383,7 @@ class Cleanup implements Job
                 $this->entityManager->removeEntity($attachment);
             }
 
-            $select = $this->entityManager->createSelectBuilder()
+            $delete = $this->entityManager->getQueryBuilder()->delete()
                 ->from('Email')
                 ->where([
                     'deleted' => true,
@@ -391,16 +391,16 @@ class Cleanup implements Job
                 ])
                 ->build();
 
-            $this->entityManager->getQueryExecutor()->delete($select);
+            $this->entityManager->getQueryExecutor()->run($delete);
 
-            $select = $this->entityManager->createSelectBuilder()
+            $delete = $this->entityManager->getQueryBuilder()->delete()
                 ->from('EmailUser')
                 ->where([
                     'emailId' => $id,
                 ])
                 ->build();
 
-            $this->entityManager->getQueryExecutor()->delete($select);
+            $this->entityManager->getQueryExecutor()->run($delete);
         }
     }
 
@@ -452,7 +452,7 @@ class Cleanup implements Job
         $repository = $this->entityManager->getRepository($scope);
         $repository->deleteFromDb($entity->id);
 
-        $query = $this->entityManager->getQuery();
+        $query = $this->entityManager->getQueryComposer();
 
         foreach ($entity->getRelationList() as $relation) {
             if ($entity->getRelationType($relation) !== Entity::MANY_MANY) {
@@ -492,12 +492,12 @@ class Cleanup implements Job
                     continue;
                 }
 
-                $select = $this->entityManager->createSelectBuilder()
+                $delete = $this->entityManager->getQueryBuilder()->delete()
                     ->from($relationEntityType)
                     ->where($where)
                     ->build();
 
-                $this->entityManager->getQueryExecutor()->delete($select);
+                $this->entityManager->getQueryExecutor()->run($delete);
 
             } catch (\Exception $e) {
                 $GLOBALS['log']->error("Cleanup: " . $e->getMessage());
diff --git a/application/Espo/Modules/Crm/Core/Formula/Functions/ExtGroup/AccountGroup/FindByEmailAddressType.php b/application/Espo/Modules/Crm/Core/Formula/Functions/ExtGroup/AccountGroup/FindByEmailAddressType.php
index 01e552e164..4f9803202c 100644
--- a/application/Espo/Modules/Crm/Core/Formula/Functions/ExtGroup/AccountGroup/FindByEmailAddressType.php
+++ b/application/Espo/Modules/Crm/Core/Formula/Functions/ExtGroup/AccountGroup/FindByEmailAddressType.php
@@ -85,7 +85,7 @@ class FindByEmailAddressType extends BaseFunction implements
 
         if ($contact) {
             if (!in_array($domain, $ignoreList)) {
-                $account = $em->getRepository('Account')->join(['contacts'])->where([
+                $account = $em->getRepository('Account')->join('contacts')->where([
                     'emailAddress*' => '%' . $domain,
                     'contacts.id' => $contact->id,
                 ])->findOne();
diff --git a/application/Espo/Modules/Crm/Jobs/CheckEmailAccounts.php b/application/Espo/Modules/Crm/Jobs/CheckEmailAccounts.php
index 797142a58e..e21911ce2a 100644
--- a/application/Espo/Modules/Crm/Jobs/CheckEmailAccounts.php
+++ b/application/Espo/Modules/Crm/Jobs/CheckEmailAccounts.php
@@ -77,11 +77,13 @@ class CheckEmailAccounts implements JobTargeted
 
     public function prepare(ScheduledJob $scheduledJob, string $executeTime)
     {
-        $collection = $this->entityManager->getRepository('EmailAccount')->join([['assignedUser', 'assignedUserAdditional']])->where([
-            'status' => 'Active',
-            'useImap' => true,
-            'assignedUserAdditional.isActive' => true,
-        ])->find();
+        $collection = $this->entityManager->getRepository('EmailAccount')
+            ->join('assignedUser', 'assignedUserAdditional')
+            ->where([
+                'status' => 'Active',
+                'useImap' => true,
+                'assignedUserAdditional.isActive' => true,
+            ])->find();
 
         foreach ($collection as $entity) {
             $running = $this->entityManager->getRepository('Job')->where([
diff --git a/application/Espo/Modules/Crm/Services/Activities.php b/application/Espo/Modules/Crm/Services/Activities.php
index ce44c7ffa3..dfdec60c5c 100644
--- a/application/Espo/Modules/Crm/Services/Activities.php
+++ b/application/Espo/Modules/Crm/Services/Activities.php
@@ -167,7 +167,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Meeting', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Meeting', $selectParams);
 
         return $sql;
     }
@@ -222,7 +222,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Call', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Call', $selectParams);
 
         return $sql;
     }
@@ -272,7 +272,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Email', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Email', $selectParams);
 
         return $sql;
     }
@@ -351,7 +351,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Meeting', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Meeting', $selectParams);
 
         if ($this->isPerson($scope)) {
             $link = null;
@@ -383,7 +383,7 @@ class Activities implements
 
                 $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-                $sql .= ' UNION ' . $this->getEntityManager()->getQuery()->createSelectQuery('Meeting', $selectParams);
+                $sql .= ' UNION ' . $this->getEntityManager()->getQueryComposer()->createSelectQuery('Meeting', $selectParams);
             }
         }
 
@@ -463,7 +463,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Call', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Call', $selectParams);
 
         if ($this->isPerson($scope)) {
             $link = null;
@@ -495,7 +495,7 @@ class Activities implements
 
                 $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-                $sql .= ' UNION ' . $this->getEntityManager()->getQuery()->createSelectQuery('Call', $selectParams);
+                $sql .= ' UNION ' . $this->getEntityManager()->getQueryComposer()->createSelectQuery('Call', $selectParams);
             }
         }
 
@@ -576,7 +576,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Email', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Email', $selectParams);
 
         if ($this->isPerson($scope) || $this->isCompany($scope)) {
             $selectParams = $baseSelectParams;
@@ -600,7 +600,7 @@ class Activities implements
 
             $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-            $sql .= "\n UNION \n" . $this->getEntityManager()->getQuery()->createSelectQuery('Email', $selectParams);
+            $sql .= "\n UNION \n" . $this->getEntityManager()->getQueryComposer()->createSelectQuery('Email', $selectParams);
 
             $selectParams = $baseSelectParams;
             $selectParams['customJoin'] .= "
@@ -626,7 +626,7 @@ class Activities implements
 
             $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-            $sql .= "\n UNION \n" . $this->getEntityManager()->getQuery()->createSelectQuery('Email', $selectParams);
+            $sql .= "\n UNION \n" . $this->getEntityManager()->getQueryComposer()->createSelectQuery('Email', $selectParams);
         }
 
         return $sql;
@@ -804,7 +804,7 @@ class Activities implements
 
         $sql = $this->getActivitiesQuery($entity, $entityType, $statusList, $isHistory, $selectParams);
 
-        $query = $this->getEntityManager()->getQuery();
+        $query = $this->getEntityManager()->getQueryComposer();
 
         $seed = $this->getEntityManager()->getEntity($entityType);
 
@@ -816,7 +816,7 @@ class Activities implements
 
         $sql = $query->limit($sql, $offset, $limit);
 
-        $collection = $this->getEntityManager()->getRepository($entityType)->findByQuery($sql);
+        $collection = $this->getEntityManager()->getRepository($entityType)->findBySql($sql);
 
         foreach ($collection as $e) {
             $service->loadAdditionalFieldsForList($e);
@@ -843,7 +843,7 @@ class Activities implements
         ];
     }
 
-    public function getActivities($scope, $id, $params = [])
+    public function getActivities(string $scope, string $id, array $params = [])
     {
         $entity = $this->getEntityManager()->getEntity($scope, $id);
         if (!$entity) {
@@ -969,7 +969,7 @@ class Activities implements
             $selectManager->applyAccess($selectParams);
         }
 
-        return $this->getEntityManager()->getQuery()->createSelectQuery('Meeting', $selectParams);
+        return $this->getEntityManager()->getQueryComposer()->createSelectQuery('Meeting', $selectParams);
     }
 
     protected function getCalendarCallQuery($userId, $from, $to, $skipAcl)
@@ -1025,7 +1025,7 @@ class Activities implements
             $selectManager->applyAccess($selectParams);
         }
 
-        return $this->getEntityManager()->getQuery()->createSelectQuery('Call', $selectParams);
+        return $this->getEntityManager()->getQueryComposer()->createSelectQuery('Call', $selectParams);
     }
 
     protected function getCalendarTaskQuery($userId, $from, $to, $skipAcl = false)
@@ -1088,7 +1088,7 @@ class Activities implements
             $selectManager->applyAccess($selectParams);
         }
 
-        return $this->getEntityManager()->getQuery()->createSelectQuery('Task', $selectParams);
+        return $this->getEntityManager()->getQueryComposer()->createSelectQuery('Task', $selectParams);
     }
 
     protected function getCalendarSelectParams($scope, $userId, $from, $to, $skipAcl = false)
@@ -1182,7 +1182,7 @@ class Activities implements
         $selectManager = $this->getSelectManagerFactory()->create($scope);
         if (method_exists($selectManager, 'getCalendarSelectParams')) {
             $selectParams = $selectManager->getCalendarSelectParams($userId, $from, $to, $skipAcl);
-            return $this->getEntityManager()->getQuery()->createSelectQuery($scope, $selectParams);
+            return $this->getEntityManager()->getQueryComposer()->createSelectQuery($scope, $selectParams);
         }
 
         $methodName = 'getCalendar' . $scope . 'Query';
@@ -1191,7 +1191,7 @@ class Activities implements
         }
 
         $selectParams = $this->getCalendarSelectParams($scope, $userId, $from, $to, $skipAcl);
-        return $this->getEntityManager()->getQuery()->createSelectQuery($scope, $selectParams);
+        return $this->getEntityManager()->getQueryComposer()->createSelectQuery($scope, $selectParams);
     }
 
     protected function getActivitiesQuery(Entity $entity, $scope, array $statusList = [], $isHistory = false, $additinalSelectParams = null)
@@ -1211,7 +1211,7 @@ class Activities implements
 
             $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-            return $this->getEntityManager()->getQuery()->createSelectQuery($scope, $selectParams);
+            return $this->getEntityManager()->getQueryComposer()->createSelectQuery($scope, $selectParams);
         }
 
         $methodName = 'getActivities' . $scope . 'Query';
@@ -1223,7 +1223,7 @@ class Activities implements
 
         $selectParams = $selectManager->mergeSelectParams($selectParams, $additinalSelectParams);
 
-        return $this->getEntityManager()->getQuery()->createSelectQuery($scope, $selectParams);
+        return $this->getEntityManager()->getQueryComposer()->createSelectQuery($scope, $selectParams);
     }
 
     protected function getActivitiesSelectParams(Entity $entity, $scope, array $statusList = [], $isHistory)
@@ -1403,10 +1403,15 @@ class Activities implements
 
         $userIdList = [];
 
-        $userList = $this->getEntityManager()->getRepository('User')->select(['id', 'name'])->leftJoin([['teams', 'teams']])->where([
-            'isActive' => true,
-            'teamsMiddle.teamId' => $teamIdList
-        ])->distinct()->find([], true);
+        $userList = $this->getEntityManager()->getRepository('User')
+            ->select(['id', 'name'])
+            ->leftJoin('teams')
+            ->where([
+                'isActive' => true,
+                'teamsMiddle.teamId' => $teamIdList
+            ])
+            ->distinct()
+            ->find();
 
         $userNames = (object) [];
 
@@ -1667,6 +1672,7 @@ class Activities implements
     public function getUpcomingActivities($userId, $params = [], $entityTypeList = null, $futureDays = null)
     {
         $user = $this->getEntityManager()->getEntity('User', $userId);
+
         $this->accessCheck($user);
 
         if (!$entityTypeList) {
@@ -1682,6 +1688,8 @@ class Activities implements
         $taskBeforeString = (new \DateTime())->modify('+' . $upcomingTaskFutureDays . ' days')->format('Y-m-d H:i:s');
 
         $unionPartList = [];
+
+
         foreach ($entityTypeList as $entityType) {
             if (!$this->getMetadata()->get(['scopes', $entityType, 'activity']) && $entityType !== 'Task') continue;
             if (!$this->getAcl()->checkScope($entityType, 'read')) continue;
@@ -1771,8 +1779,7 @@ class Activities implements
                     ]
                 ], $selectParams);
             }
-
-            $sql = $this->getEntityManager()->getQuery()->createSelectQuery($entityType, $selectParams);
+            $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery($entityType, $selectParams);
 
             $unionPartList[] = '' . $sql . '';
         }
@@ -1817,7 +1824,7 @@ class Activities implements
 
         return [
             'total' => $totalCount,
-            'list' => $entityDataList
+            'list' => $entityDataList,
         ];
     }
 }
diff --git a/application/Espo/Modules/Crm/Services/Campaign.php b/application/Espo/Modules/Crm/Services/Campaign.php
index 03aca85389..83c7c296e8 100644
--- a/application/Espo/Modules/Crm/Services/Campaign.php
+++ b/application/Espo/Modules/Crm/Services/Campaign.php
@@ -160,7 +160,7 @@ class Campaign extends \Espo\Services\Record implements
 
             $this->getEntityManager()->getRepository('Opportunity')->handleSelectParams($params);
 
-            $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Opportunity', $params);
+            $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Opportunity', $params);
 
             $pdo = $this->getEntityManager()->getPDO();
             $sth = $pdo->prepare($sql);
diff --git a/application/Espo/Modules/Crm/Services/MassEmail.php b/application/Espo/Modules/Crm/Services/MassEmail.php
index d219e6d191..2a52c72b26 100644
--- a/application/Espo/Modules/Crm/Services/MassEmail.php
+++ b/application/Espo/Modules/Crm/Services/MassEmail.php
@@ -86,21 +86,21 @@ class MassEmail extends \Espo\Services\Record implements
     {
         parent::afterDeleteEntity($massEmail);
 
-        $selectParams = $this->getEntityManager()->createSelectBuilder()
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
             ->from('EmailQueueItem')
             ->where([
                  'massEmailId' => $massEmail->id,
             ])
             ->build();
 
-        $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('EmailQueueItem', $selectParams->getRaw());
-
-        $this->getEntityManager()->runQuery($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
     }
 
     protected function cleanupQueueItems(Entity $massEmail)
     {
-        $selectParams = $this->getEntityManager()->createSelectBuilder()
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
             ->from('EmailQueueItem')
             ->where([
                  'massEmailId' => $massEmail->id,
@@ -108,9 +108,7 @@ class MassEmail extends \Espo\Services\Record implements
             ])
             ->build();
 
-        $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('EmailQueueItem', $selectParams->getRaw());
-
-        $this->getEntityManager()->runQuery($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
     }
 
     public function createQueue(Entity $massEmail, bool $isTest = false, $additionalTargetList = [])
diff --git a/application/Espo/Modules/Crm/Services/Opportunity.php b/application/Espo/Modules/Crm/Services/Opportunity.php
index 43aa3132dd..51fb678cee 100644
--- a/application/Espo/Modules/Crm/Services/Opportunity.php
+++ b/application/Espo/Modules/Crm/Services/Opportunity.php
@@ -99,7 +99,7 @@ class Opportunity extends \Espo\Services\Record
 
         $this->getEntityManager()->getRepository('Opportunity')->handleSelectParams($selectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Opportunity', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Opportunity', $selectParams);
 
         $sth = $pdo->prepare($sql);
         $sth->execute();
@@ -176,7 +176,7 @@ class Opportunity extends \Espo\Services\Record
 
         $this->getEntityManager()->getRepository('Opportunity')->handleSelectParams($selectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Opportunity', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Opportunity', $selectParams);
 
         $sth = $pdo->prepare($sql);
         $sth->execute();
@@ -234,7 +234,7 @@ class Opportunity extends \Espo\Services\Record
 
         $this->getEntityManager()->getRepository('Opportunity')->handleSelectParams($selectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Opportunity', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Opportunity', $selectParams);
 
         $sth = $pdo->prepare($sql);
         $sth->execute();
@@ -294,7 +294,7 @@ class Opportunity extends \Espo\Services\Record
 
         $this->getEntityManager()->getRepository('Opportunity')->handleSelectParams($selectParams);
 
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Opportunity', $selectParams);
+        $sql = $this->getEntityManager()->getQueryComposer()->createSelectQuery('Opportunity', $selectParams);
 
         $sth = $pdo->prepare($sql);
         $sth->execute();
diff --git a/application/Espo/Modules/Crm/Services/TargetList.php b/application/Espo/Modules/Crm/Services/TargetList.php
index 003d01585f..232a0d9a7f 100644
--- a/application/Espo/Modules/Crm/Services/TargetList.php
+++ b/application/Espo/Modules/Crm/Services/TargetList.php
@@ -111,7 +111,7 @@ class TargetList extends \Espo\Services\Record
 
         foreach ($this->targetsLinkList as $link) {
             $foreignEntityType = $entity->getRelationParam($link, 'entity');
-            $count += $this->getEntityManager()->getRepository($foreignEntityType)->join(['targetLists'])->where([
+            $count += $this->getEntityManager()->getRepository($foreignEntityType)->join('targetLists')->where([
                 'targetListsMiddle.targetListId' => $entity->id,
                 'targetListsMiddle.optedOut' => 1,
             ])->count();
@@ -209,7 +209,7 @@ class TargetList extends \Espo\Services\Record
         }
 
         $pdo = $this->getEntityManager()->getPDO();
-        $query = $this->getEntityManager()->getQuery();
+        $query = $this->getEntityManager()->getQueryComposer();
         $sql = null;
 
         switch ($link) {
@@ -237,7 +237,7 @@ class TargetList extends \Espo\Services\Record
     protected function findLinkedOptedOut(string $id, array $params) : RecordCollection
     {
         $pdo = $this->getEntityManager()->getPDO();
-        $query = $this->getEntityManager()->getQuery();
+        $query = $this->getEntityManager()->getQueryComposer();
 
         $sqlContact = $query->createSelectQuery('Contact', array(
             'select' => ['id', 'name', 'createdAt', ['VALUE:Contact', '_scope']],
diff --git a/application/Espo/ORM/Collection.php b/application/Espo/ORM/Collection.php
index a57bb0c116..0f85dc2279 100644
--- a/application/Espo/ORM/Collection.php
+++ b/application/Espo/ORM/Collection.php
@@ -29,10 +29,12 @@
 
 namespace Espo\ORM;
 
+use Traversable;
+
 /**
  * A collection of entities.
  */
-interface Collection extends \Traversable
+interface Collection extends Traversable
 {
     /**
      * Get an array of StdClass objects.
diff --git a/application/Espo/ORM/RDBQueryExecutor.php b/application/Espo/ORM/CollectionFactory.php
similarity index 67%
rename from application/Espo/ORM/RDBQueryExecutor.php
rename to application/Espo/ORM/CollectionFactory.php
index 8d5a969dc7..0da836f2f2 100644
--- a/application/Espo/ORM/RDBQueryExecutor.php
+++ b/application/Espo/ORM/CollectionFactory.php
@@ -29,12 +29,14 @@
 
 namespace Espo\ORM;
 
+use Espo\ORM\{
+    QueryParams\Select,
+};
+
 /**
- * Executes queries by a given RDBSelect instances.
- *
- * @todo Add `select` method returning an array of StdClass objects.
+ * Creates collections.
  */
-class RDBQueryExecutor
+class CollectionFactory
 {
     protected $entityManager;
 
@@ -43,20 +45,23 @@ class RDBQueryExecutor
         $this->entityManager = $entityManager;
     }
 
-    public function update(RDBSelect $select, array $values)
+    public function create(?string $entityType = null, array $data = []) : EntityCollection
     {
-        $params = $select->getRawParams();
-        $params['update'] = $values;
-
-        $sql = $this->entityManager->getQuery()->createUpdateQuery($select->getEntityType(), $params);
-
-        $this->entityManager->runQuery($sql, true);
+        return new EntityCollection($data, $entityType, $this->entityManager->getEntityFactory());
     }
 
-    public function delete(RDBSelect $select)
+    public function createFromSql(string $entityType, string $sql) : SthCollection
     {
-        $sql = $this->entityManager->getQuery()->createDeleteQuery($select->getEntityType(), $select->getRawParams());
+        return SthCollection::fromSql($entityType, $sql, $this->entityManager);
+    }
 
-        $this->entityManager->runQuery($sql, true);
+    public function createFromQuery(Select $query) : SthCollection
+    {
+        return SthCollection::fromQuery($query, $this->entityManager);
+    }
+
+    public function createFromSthCollection(SthCollection $sthCollection) : EntityCollection
+    {
+        return EntityCollection::fromSthCollection($sthCollection);
     }
 }
diff --git a/application/Espo/ORM/DB/Query/Base.php b/application/Espo/ORM/DB/Query/Base.php
index cc6f5603e2..c3e85ec993 100644
--- a/application/Espo/ORM/DB/Query/Base.php
+++ b/application/Espo/ORM/DB/Query/Base.php
@@ -32,7 +32,7 @@ namespace Espo\ORM\DB\Query;
 /**
  * @deprecated
  */
-abstract class Base extends BaseQuery
+abstract class Base extends Espo\ORM\QueryComposer\BaseQueryComposer
 {
 
 }
diff --git a/application/Espo/ORM/EntityCollection.php b/application/Espo/ORM/EntityCollection.php
index b8c408c6a1..c671055a5d 100644
--- a/application/Espo/ORM/EntityCollection.php
+++ b/application/Espo/ORM/EntityCollection.php
@@ -29,10 +29,15 @@
 
 namespace Espo\ORM;
 
+use Iterator;
+use Countable;
+use ArrayAccess;
+use SeekableIterator;
+
 /**
  * A standard collection of entities. It allocates a memory for all entities.
  */
-class EntityCollection implements \Iterator, \Countable, \ArrayAccess, \SeekableIterator, Collection
+class EntityCollection implements Collection, Iterator, Countable, ArrayAccess, SeekableIterator
 {
     private $entityFactory = null;
 
@@ -300,4 +305,19 @@ class EntityCollection implements \Iterator, \Countable, \ArrayAccess, \Seekable
     {
         return $this->isFetched;
     }
+
+    public static function fromSthCollection(SthCollection $sthCollection) : self
+    {
+        $entityList = [];
+
+        foreach ($sthCollection as $entity) {
+            $entityList[] = $entity;
+        }
+
+        $obj = new EntityCollection($entityList, $sthCollection->getEntityType());
+
+        $obj->setAsFetched();
+
+        return $obj;
+    }
 }
diff --git a/application/Espo/ORM/EntityManager.php b/application/Espo/ORM/EntityManager.php
index 17bf19850c..0b74b654f3 100644
--- a/application/Espo/ORM/EntityManager.php
+++ b/application/Espo/ORM/EntityManager.php
@@ -29,15 +29,17 @@
 
 namespace Espo\ORM;
 
-use Espo\Core\Exceptions\Error;
-
-use Espo\ORM\DB\{
-    Mapper,
-    Query\BaseQuery as Query,
+use Espo\ORM\{
+    Mapper\Mapper,
+    QueryComposer\QueryComposer,
+    Repository\RepositoryFactory,
+    Repository\Repository,
 };
 
 use PDO;
+use PDOStatement;
 use Exception;
+use RuntimeException;
 
 /**
  * A central access point to ORM functionality.
@@ -50,6 +52,8 @@ class EntityManager
 
     protected $entityFactory;
 
+    protected $collectionFactory;
+
     protected $repositoryFactory;
 
     protected $mappers = [];
@@ -60,7 +64,7 @@ class EntityManager
 
     protected $params = [];
 
-    protected $query;
+    protected $queryComposer;
 
     protected $defaultMapperName = 'RDB';
 
@@ -95,20 +99,43 @@ class EntityManager
 
         $this->repositoryFactory = $repositoryFactory;
 
-        $this->queryExecutor = new RDBQueryExecutor($this);
+        $this->initQueryComposer();
+
+        $this->queryExecutor = new QueryExecutor($this);
+
+        $this->queryBuilder = new QueryBuilder();
+
+        $this->collectionFactory = new CollectionFactory($this);
+    }
+
+    protected function initQueryComposer()
+    {
+        $className = $this->params['queryComposerClassName'] ?? null;
+
+        if (!$className) {
+            $platform = $this->params['platform'];
+            $className = 'Espo\\ORM\\QueryComposer\\' . ucfirst($platform) . 'QueryComposer';
+        }
+
+        if (!$className || !class_exists($className)) {
+            throw new RuntimeException("Query composer {$name} could not be created.");
+        }
+
+        $this->queryComposer = new $className($this->getPDO(), $this->entityFactory, $this->metadata);
     }
 
     /**
-     * Get a Query.
+     * @todo Remove in v7.0.
+     * @deprecated
      */
-    public function getQuery() : Query
+    public function getQuery() : QueryComposer
     {
-        if (empty($this->query)) {
-            $platform = $this->params['platform'];
-            $className = 'Espo\\ORM\\DB\\Query\\' . ucfirst($platform) . 'Query';
-            $this->query = new $className($this->getPDO(), $this->entityFactory, $this->metadata);
-        }
-        return $this->query;
+        return $this->queryComposer;
+    }
+
+    public function getQueryComposer() : QueryComposer
+    {
+        return $this->queryComposer;
     }
 
     protected function getMapperClassName(string $name) : string
@@ -118,12 +145,12 @@ class EntityManager
         switch ($name) {
             case 'RDB':
                 $platform = $this->params['platform'];
-                $className = 'Espo\\ORM\\DB\\' . ucfirst($platform) . 'Mapper';
+                $className = 'Espo\\ORM\\Mapper\\' . ucfirst($platform) . 'Mapper';
                 break;
         }
 
         if (!$className || !class_exists($className)) {
-            throw new Error("Mapper {$name} does not exist.");
+            throw new RuntimeException("Mapper '{$name}' does not exist.");
         }
 
         return $className;
@@ -140,7 +167,7 @@ class EntityManager
 
         if (empty($this->mappers[$className])) {
             $this->mappers[$className] = new $className(
-                $this->getPDO(), $this->entityFactory, $this->getQuery(), $this->metadata
+                $this->getPDO(), $this->entityFactory, $this->collectionFactory, $this->getQueryComposer(), $this->metadata
             );
         }
 
@@ -187,7 +214,7 @@ class EntityManager
     public function getEntity(string $entityType, ?string $id = null) : ?Entity
     {
         if (!$this->hasRepository($entityType)) {
-            throw new Error("ORM: Repository '{$entityType}' does not exist.");
+            throw new RuntimeException("ORM: Repository '{$entityType}' does not exist.");
         }
 
         return $this->getRepository($entityType)->get($id);
@@ -214,7 +241,7 @@ class EntityManager
     }
 
     /**
-     * Create entity (store it in database).
+     * Create entity (store it in a database).
      *
      * @param StdClass|array $data Entity attributes.
      */
@@ -222,13 +249,14 @@ class EntityManager
     {
         $entity = $this->getEntity($entityType);
         $entity->set($data);
+
         $this->saveEntity($entity, $options);
 
         return $entity;
     }
 
     /**
-     * Fetch an entity (from database).
+     * Fetch an entity (from a database).
      */
     public function fetchEntity(string $entityType, string $id) : ?Entity
     {
@@ -253,7 +281,7 @@ class EntityManager
     public function getRepository(string $entityType) : ?Repository
     {
         if (!$this->hasRepository($entityType)) {
-            throw new Error("Repository '{$entityType}' does not exist.");
+            throw new RuntimeException("Repository '{$entityType}' does not exist.");
         }
 
         if (empty($this->repositoryHash[$entityType])) {
@@ -264,13 +292,17 @@ class EntityManager
     }
 
     /**
-     * Create a select builder.
+     * Get a query builder.
      */
-    public function createSelectBuilder() : RDBSelectBuilder
+    public function getQueryBuilder() : QueryBuilder
     {
-        return new RDBSelectBuilder($this);
+        return $this->queryBuilder;
     }
 
+    /**
+     * @deprecated
+     * @todo Remove.
+     */
     public function setMetadata(array $data)
     {
         $this->metadata->setData($data);
@@ -282,7 +314,7 @@ class EntityManager
     }
 
     /**
-     * Get an instance of PDO.
+     * Get a PDO instance.
      */
     public function getPDO() : PDO
     {
@@ -294,19 +326,11 @@ class EntityManager
     }
 
     /**
-     * Create a collection. Entity type can be omitted.
+     * Create a collection. An entity type can be omitted.
      */
     public function createCollection(?string $entityType = null, array $data = []) : EntityCollection
     {
-        return new EntityCollection($data, $entityType, $this->entityFactory);
-    }
-
-    /**
-     * Create an STH collection. An STH collection is preferable when a select query returns a large number of rows.
-     */
-    public function createSthCollection(string $entityType, array $selectParams = []) : SthCollection
-    {
-        return new SthCollection($entityType, $this, $selectParams);
+        return $this->collectionFactory->create($data, $entityType);
     }
 
     public function getEntityFactory() : EntityFactory
@@ -314,30 +338,56 @@ class EntityManager
         return $this->entityFactory;
     }
 
+    public function getCollectionFactory() : CollectionFactory
+    {
+        return $this->collectionFactory;
+    }
+
     /**
      * Get a Query Executor.
      */
-    public function getQueryExecutor() : RDBQueryExecutor
+    public function getQueryExecutor() : QueryExecutor
     {
         return $this->queryExecutor;
     }
 
     /**
-     * Run a query. Returns a result.
+     * Run a Query.
+     */
+    public function runQuery(Query $query) : PDOStatement
+    {
+        return $this->queryExecutor->run($query);
+    }
+
+    /**
+     * Run a SQL query.
      *
      * @param $rerunIfDeadlock Query will be re-run if a deadlock occurs.
      */
-    public function runQuery(string $query, bool $rerunIfDeadlock = false)
+    public function runSql(string $sql, bool $rerunIfDeadlock = false) : PDOStatement
     {
+        $pdoStatement = null;
+
         try {
-            return $this->getPDO()->query($query);
+            $pdoStatement = $this->getPDO()->query($sql);
         } catch (Exception $e) {
-            if ($rerunIfDeadlock) {
-                if (isset($e->errorInfo) && $e->errorInfo[0] == 40001 && $e->errorInfo[1] == 1213) {
-                    return $this->getPDO()->query($query);
-                }
+            if (!$rerunIfDeadlock) {
+                throw $e;
+            }
+
+            if (isset($e->errorInfo) && $e->errorInfo[0] == 40001 && $e->errorInfo[1] == 1213) {
+                $pdoStatement = $this->getPDO()->query($sql);
+            }
+
+            if (!$pdoStatement) {
+                throw $e;
             }
-            throw $e;
         }
+
+        if (!$pdoStatement) {
+            throw new RuntimeException("Query execution failure.");
+        }
+
+        return $pdoStatement;
     }
 }
diff --git a/application/Espo/ORM/DB/BaseMapper.php b/application/Espo/ORM/Mapper/BaseMapper.php
similarity index 67%
rename from application/Espo/ORM/DB/BaseMapper.php
rename to application/Espo/ORM/Mapper/BaseMapper.php
index 33df6a2f0e..1c3ac0270b 100644
--- a/application/Espo/ORM/DB/BaseMapper.php
+++ b/application/Espo/ORM/Mapper/BaseMapper.php
@@ -27,16 +27,21 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB;
+namespace Espo\ORM\Mapper;
 
 use Espo\ORM\{
     Entity,
     Collection,
     EntityFactory,
+    CollectionFactory,
     Metadata,
-    DB\Query\BaseQuery as Query,
+    QueryComposer\QueryComposer,
     EntityCollection,
-    Sth2Collection,
+    SthCollection,
+    QueryParams\Select,
+    QueryParams\Update,
+    QueryParams\Delete,
+    QueryParams\Insert,
 };
 
 use PDO;
@@ -49,7 +54,9 @@ use RuntimeException;
  */
 abstract class BaseMapper implements Mapper
 {
-    public $pdo;
+    const ATTRIBUTE_DELETED = 'deleted';
+
+    protected $pdo;
 
     protected $entityFactroy;
 
@@ -61,93 +68,117 @@ abstract class BaseMapper implements Mapper
 
     protected $aliasesCache = [];
 
-    protected $collectionClass = EntityCollection::class;
-
-    protected $sthCollectionClass = Sth2Collection::class;
-
-    public function __construct(PDO $pdo, EntityFactory $entityFactory, Query $query, Metadata $metadata)
-    {
+    public function __construct(
+        PDO $pdo, EntityFactory $entityFactory, CollectionFactory $collectionFactory, QueryComposer $queryComposer, Metadata $metadata
+    ) {
         $this->pdo = $pdo;
-        $this->query = $query;
+        $this->queryComposer = $queryComposer;
         $this->entityFactory = $entityFactory;
+        $this->collectionFactory = $collectionFactory;
         $this->metadata = $metadata;
 
         $this->helper = new Helper($metadata);
     }
 
     /**
-     * Get a single entity from DB by ID.
+     * Get the first entity from DB.
      */
-    public function selectById(Entity $entity, string $id, ?array $params = null) : ?Entity
+    public function selectOne(Select $select) : ?Entity
     {
-        $params = $params ?? [];
+        $entityType = $select->getFrom();
 
-        if (!array_key_exists('whereClause', $params)) {
-            $params['whereClause'] = [];
-        }
+        $entity = $this->entityFactory->create($entityType);
 
-        $params['whereClause']['id'] = $id;
-
-        $sql = $this->query->createSelectQuery($entity->getEntityType(), $params);
+        $sql = $this->queryComposer->compose($select);
 
         $ps = $this->pdo->query($sql);
 
-        if ($ps) {
-            foreach ($ps as $row) {
-                $entity = $this->fromRow($entity, $row);
-                $entity->setAsFetched();
-                return $entity;
-            }
+        if (!$ps) {
+            return null;
         }
+
+        foreach ($ps as $row) {
+            $this->populateEntityFromRow($entity, $row);
+            $entity->setAsFetched();
+
+            return $entity;
+        }
+
         return null;
     }
 
     /**
      * Get a number of entities in DB.
      */
-    public function count(Entity $entity, ?array $params = null) : int
+    public function count(Select $select) : int
     {
-        return (int) $this->aggregate($entity, $params, 'COUNT', 'id');
+        return (int) $this->aggregate($select, 'COUNT', 'id');
     }
 
-    public function max(Entity $entity, ?array $params, string $attribute)
+    public function max(Select $select, string $attribute)
     {
-        return $this->aggregate($entity, $params, 'MAX', $attribute);
+         $value =  $this->aggregate($select, 'MAX', $attribute);
+
+         return $this->castToNumber($value);
     }
 
-    public function min(Entity $entity, ?array $params, string $attribute)
+    public function min(Select $select, string $attribute)
     {
-        return $this->aggregate($entity, $params, 'MIN', $attribute);
+        $value = $this->aggregate($select, 'MIN', $attribute);
+
+        return $this->castToNumber($value);
     }
 
-    public function sum(Entity $entity, ?array $params, string $attribute)
+    public function sum(Select $select, string $attribute)
     {
-        return $this->aggregate($entity, $params, 'SUM', $attribute);
+        $value = $this->aggregate($select, 'SUM', $attribute);
+
+        return $this->castToNumber($value);
+    }
+
+    protected function castToNumber($value)
+    {
+        if (is_int($value) || is_float($value)) {
+            return $value;
+        }
+
+        if (!is_string($value)) {
+            return 0;
+        }
+
+        if (strpos($value, '.') !== false) {
+            return (float) $value;
+        }
+
+        return (int) $value;
     }
 
     /**
      * Select enities from DB.
      */
-    public function select(Entity $entity, ?array $params = null) : Collection
+    public function select(Select $select) : Collection
     {
-        $sql = $this->query->createSelectQuery($entity->getEntityType(), $params);
+        $entityType = $select->getFrom();
 
-        return $this->selectByQuery($entity, $sql, $params);
+        $sql = $this->queryComposer->compose($select);
+
+        return $this->selectBySqlInternal($entityType, $sql, $select->isSth());
     }
 
     /**
      * Select enities from DB by a SQL query.
      */
-    public function selectByQuery(Entity $entity, string $sql, ?array $params = null) : Collection
+    public function selectBySql(string $entityType, string $sql) : SthCollection
+    {
+        return $this->selectBySqlInternal($entityType, $sql, true);
+    }
+
+    protected function selectBySqlInternal(string $entityType, string $sql, bool $returnSthCollection = false) : Collection
     {
         $params = $params ?? [];
 
-        if ($params['returnSthCollection'] ?? false) {
-            $collection = $this->createSthCollection($entity->getEntityType());
-            $collection->setQuery($sql);
-            $collection->setAsFetched();
-
-            return $collection;
+        if ($returnSthCollection) {
+            return $this->collectionFactory->createFromSql($entityType, $sql);
         }
 
         $dataList = [];
@@ -156,63 +187,63 @@ abstract class BaseMapper implements Mapper
             $dataList = $ps->fetchAll();
         }
 
-        $collection = $this->createCollection($entity->getEntityType(), $dataList);
+        $collection = $this->collectionFactory->create($entityType, $dataList);
         $collection->setAsFetched();
 
         return $collection;
     }
 
-    protected function createCollection(string $entityType, ?array $dataList = [])
+    public function aggregate(Select $select, string $aggregation, string $aggregationBy)
     {
-        return new $this->collectionClass($dataList, $entityType, $this->entityFactory);
-    }
+        $entityType = $select->getFrom();
 
-    protected function createSthCollection(string $entityType)
-    {
-        return new $this->sthCollectionClass($entityType, $this->entityFactory, $this->query, $this->pdo);;
-    }
+        $entity = $this->entityFactory->create($entityType);
 
-    public function aggregate(Entity $entity, ?array $params, string $aggregation, string $aggregationBy)
-    {
         if (empty($aggregation) || !$entity->hasAttribute($aggregationBy)) {
-            return null;
+            throw new RuntimeException();
         }
 
-        $params = $params ?? [];
+        $params = $select->getRawParams();
 
         $params['aggregation'] = $aggregation;
         $params['aggregationBy'] = $aggregationBy;
 
-        $sql = $this->query->createSelectQuery($entity->getEntityType(), $params);
+        $select = Select::fromRaw($params);
+
+        $sql = $this->queryComposer->compose($select);
 
         $ps = $this->pdo->query($sql);
 
-        if ($ps) {
-            foreach ($ps as $row) {
-                return $row['value'];
-            }
+        if (!$ps) {
+            return null;
         }
 
-        return null;
+        foreach ($ps as $row) {
+            return $row['value'];
+        }
     }
 
     /**
      * Select related entities from DB.
      */
-    public function selectRelated(Entity $entity, string $relationName, ?array $params = null)
+    public function selectRelated(Entity $entity, string $relationName, ?Select $select = null)
     {
-        return $this->selectRelatedInternal($entity, $relationName, $params);
+        return $this->selectRelatedInternal($entity, $relationName, $select);
     }
 
-    protected function selectRelatedInternal(Entity $entity, string $relationName, ?array $params = null, bool $returnTotalCount = false)
+    protected function selectRelatedInternal(Entity $entity, string $relationName, ?Select $select = null, bool $returnTotalCount = false)
     {
-        $params = $params ?? [];
+        $params = [];
+
+        if ($select) {
+            $params = $select->getRawParams();
+        }
 
         $entityType = $entity->getEntityType();
 
         $relDefs = $entity->getRelations()[$relationName];
 
-        if (!isset($relDefs['type'])) {
+        if (!$entity->getRelationType($relationName)) {
             throw new LogicException(
                 "Missing 'type' in definition for relationship {$relationName} in {entityType} entity."
             );
@@ -225,7 +256,7 @@ abstract class BaseMapper implements Mapper
                 );
             }
 
-            $relEntityType = (!empty($relDefs['class'])) ? $relDefs['class'] : $relDefs['entity'];
+            $relEntityType = $entity->getRelationParam($relationName, 'entity');
             $relEntity = $this->entityFactory->create($relEntityType);
         }
 
@@ -250,8 +281,9 @@ abstract class BaseMapper implements Mapper
                 $params['whereClause'][$foreignKey] = $entity->get($key);
                 $params['offset'] = 0;
                 $params['limit'] = 1;
+                $params['from'] = $relEntity->getEntityType();
 
-                $sql = $this->query->createSelectQuery($relEntity->getEntityType(), $params);
+                $sql = $this->queryComposer->compose(Select::fromRaw($params));
 
                 $ps = $this->pdo->query($sql);
 
@@ -261,13 +293,13 @@ abstract class BaseMapper implements Mapper
 
                 if ($returnTotalCount) {
                     foreach ($ps as $row) {
-                        return intval($row['value']);
+                        return (int) $row['value'];
                     }
                     return 0;
                 }
 
                 foreach ($ps as $row) {
-                    $relEntity = $this->fromRow($relEntity, $row);
+                    $this->populateEntityFromRow($relEntity, $row);
                     $relEntity->setAsFetched();
 
                     return $relEntity;
@@ -296,14 +328,13 @@ abstract class BaseMapper implements Mapper
 
                 $resultDataList = [];
 
-                $sql = $this->query->createSelectQuery($relEntity->getEntityType(), $params);
+                $params['from'] = $relEntity->getEntityType();
+
+                $sql = $this->queryComposer->compose(Select::fromRaw($params));
 
                 if (!$returnTotalCount) {
                     if (!empty($params['returnSthCollection']) && $relType !== Entity::HAS_ONE) {
-                        $collection = $this->createSthCollection($relEntity->getEntityType());
-                        $collection->setQuery($sql);
-                        $collection->setAsFetched();
-                        return $collection;
+                        return $this->collectionFactory->createFromSql($relEntity->getEntityType(), $sql);
                     }
                 }
 
@@ -315,7 +346,7 @@ abstract class BaseMapper implements Mapper
 
                 if ($returnTotalCount) {
                     foreach ($ps as $row) {
-                        return intval($row['value']);
+                        return (int) $row['value'];
                     }
                     return 0;
                 }
@@ -324,7 +355,7 @@ abstract class BaseMapper implements Mapper
 
                 if ($relType == Entity::HAS_ONE) {
                     if (count($resultDataList)) {
-                        $relEntity = $this->fromRow($relEntity, $resultDataList[0]);
+                        $this->populateEntityFromRow($relEntity, $resultDataList[0]);
                         $relEntity->setAsFetched();
 
                         return $relEntity;
@@ -332,34 +363,26 @@ abstract class BaseMapper implements Mapper
                     return null;
                 }
 
-                $collection = $this->createCollection($relEntity->getEntityType(), $resultDataList);
+                $collection = $this->collectionFactory->create($relEntity->getEntityType(), $resultDataList);
                 $collection->setAsFetched();
 
                 return $collection;
 
             case Entity::MANY_MANY:
-                $additionalColumnsConditions = null;
-                if (!empty($params['additionalColumnsConditions'])) {
-                    $additionalColumnsConditions = $params['additionalColumnsConditions'];
-                }
 
                 $params['joins'] = $params['joins'] ?? [];
 
-                $params['joins'][] = $this->getManyManyJoin($entity, $relationName, $additionalColumnsConditions);
+                $params['joins'][] = $this->getManyManyJoin($entity, $relationName);
 
-                $params['relationName'] = $relDefs['relationName'];
+                $params['from'] = $relEntity->getEntityType();
 
-                $sql = $this->query->createSelectQuery($relEntity->getEntityType(), $params);
+                $sql = $this->queryComposer->compose(Select::fromRaw($params));
 
                 $resultDataList = [];
 
                 if (!$returnTotalCount) {
                     if (!empty($params['returnSthCollection'])) {
-                        $collection = $this->createSthCollection($relEntity->getEntityType());
-                        $collection->setQuery($sql);
-                        $collection->setAsFetched();
-
-                        return $collection;
+                        return $this->collectionFactory->createFromSql($relEntity->getEntityType(), $sql);
                     }
                 }
 
@@ -371,14 +394,14 @@ abstract class BaseMapper implements Mapper
 
                 if ($returnTotalCount) {
                     foreach ($ps as $row) {
-                        return intval($row['value']);
+                        return (int) $row['value'];
                     }
                     return null;
                 }
 
                 $resultDataList = $ps->fetchAll();
 
-                $collection = $this->createCollection($relEntity->getEntityType(), $resultDataList);
+                $collection = $this->collectionFactory->create($relEntity->getEntityType(), $resultDataList);
                 $collection->setAsFetched();
 
                 return $collection;
@@ -388,9 +411,7 @@ abstract class BaseMapper implements Mapper
                 $foreignEntityId = $entity->get($key);
 
                 if (!$foreignEntityType || !$foreignEntityId) {
-                    throw new LogicException(
-                        "Bad definition for relationship {$relationName} in {$entityType} entity."
-                    );
+                    return null;
                 }
 
                 $params['whereClause'][$foreignKey] = $foreignEntityId;
@@ -399,7 +420,9 @@ abstract class BaseMapper implements Mapper
 
                 $relEntity = $this->entityFactory->create($foreignEntityType);
 
-                $sql = $this->query->createSelectQuery($foreignEntityType, $params);
+                $params['from'] = $foreignEntityType;
+
+                $sql = $this->queryComposer->compose(Select::fromRaw($params));
 
                 $ps = $this->pdo->query($sql);
 
@@ -409,13 +432,13 @@ abstract class BaseMapper implements Mapper
 
                 if ($returnTotalCount) {
                     foreach ($ps as $row) {
-                        return intval($row['value']);
+                        return (int) $row['value'];
                     }
                     return 0;
                 }
 
                 foreach ($ps as $row) {
-                    $relEntity = $this->fromRow($relEntity, $row);
+                    $this->populateEntityFromRow($relEntity, $row);
                     return $relEntity;
                 }
 
@@ -430,9 +453,9 @@ abstract class BaseMapper implements Mapper
     /**
      * Get a number of related enities in DB.
      */
-    public function countRelated(Entity $entity, string $relationName, ?array $params = null) : int
+    public function countRelated(Entity $entity, string $relationName, ?Select $select = null) : int
     {
-        return (int) $this->selectRelatedInternal($entity, $relationName, $params, true);
+        return (int) $this->selectRelatedInternal($entity, $relationName, $select, true);
     }
 
     /**
@@ -478,7 +501,7 @@ abstract class BaseMapper implements Mapper
     /**
      * Update relationship columns.
      */
-    public function updateRelation(Entity $entity, string $relationName, ?string $id = null, array $columnData) : bool
+    public function updateRelationColumns(Entity $entity, string $relationName, ?string $id = null, array $columnData) : bool
     {
         if (empty($id) || empty($relationName)) {
             throw new RuntimeException("Can't update relation, empty ID or relation name.");
@@ -513,7 +536,7 @@ abstract class BaseMapper implements Mapper
                 $where = [
                     $nearKey => $entity->id,
                     $distantKey => $id,
-                    'deleted' => false,
+                    static::ATTRIBUTE_DELETED => false,
                 ];
 
                 $conditions = $entity->getRelationParam($relationName, 'conditions') ?? [];
@@ -522,12 +545,15 @@ abstract class BaseMapper implements Mapper
                     $where[$k] = $value;
                 }
 
-                $sql = $this->query->createUpdateQuery($middleName, [
-                    'whereClause' => $where,
-                    'update' => $update,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $middleName,
+                        'whereClause' => $where,
+                        'set' => $update,
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
         }
@@ -570,7 +596,7 @@ abstract class BaseMapper implements Mapper
         $where = [
             $nearKey => $entity->id,
             $distantKey => $id,
-            'deleted' => false,
+            static::ATTRIBUTE_DELETED => false,
         ];
 
         $conditions = $entity->getRelationParam($relationName, 'conditions') ?? [];
@@ -579,10 +605,13 @@ abstract class BaseMapper implements Mapper
             $where[$k] = $value;
         }
 
-        $sql = $this->query->createSelectQuery($middleName, [
-            'select' => [[$column, 'value']],
-            'whereClause' => $where,
-        ]);
+        $sql = $this->queryComposer->compose(
+            Select::fromRaw([
+                'from' => $middleName,
+                'select' => [[$column, 'value']],
+                'whereClause' => $where,
+            ])
+        );
 
         $ps = $this->pdo->query($sql);
 
@@ -594,15 +623,15 @@ abstract class BaseMapper implements Mapper
             $value = $row['value'];
 
             if ($columnType == Entity::BOOL) {
-                return boolval($value);
+                return (bool) $value;
             }
 
             if ($columnType == Entity::INT) {
-                return intval($value);
+                return (int) $value;
             }
 
             if ($columnType == Entity::FLOAT) {
-                return floatval($value);
+                return (int) $value;
             }
 
             return $value;
@@ -614,8 +643,10 @@ abstract class BaseMapper implements Mapper
     /**
      * Mass relate.
      */
-    public function massRelate(Entity $entity, string $relationName, array $params = [])
+    public function massRelate(Entity $entity, string $relationName, Select $select)
     {
+        $params = $select->getRawParams();
+
         $id = $entity->id;
 
         if (empty($id) || empty($relationName)) {
@@ -671,15 +702,18 @@ abstract class BaseMapper implements Mapper
 
                 $params['from'] = $foreignEntityType;
 
-                $sql = $this->query->createInsertQuery($middleName, [
-                    'columns' => $columns,
-                    'valuesSelectParams' => $params,
-                    'update' => [
-                        'deleted' => false,
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Insert::fromRaw([
+                        'into' => $middleName,
+                        'columns' => $columns,
+                        'valuesSelectParams' => $params,
+                        'updateSet' => [
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return;
         }
@@ -687,14 +721,14 @@ abstract class BaseMapper implements Mapper
         throw new LogicException("Relation type '{$relType}' is not supported for mass relate.");
     }
 
-    protected function runQuery(string $query, bool $rerunIfDeadlock = false)
+    protected function runSql(string $sql, bool $rerunIfDeadlock = false)
     {
         try {
-            return $this->pdo->query($query);
+            return $this->pdo->query($sql);
         } catch (Exception $e) {
             if ($rerunIfDeadlock) {
                 if (isset($e->errorInfo) && $e->errorInfo[0] == 40001 && $e->errorInfo[1] == 1213) {
-                    return $this->pdo->query($query);
+                    return $this->pdo->query($sql);
                 }
             }
             throw $e;
@@ -746,31 +780,37 @@ abstract class BaseMapper implements Mapper
                 $foreignRelationName = $entity->getRelationParam($relationName, 'foreign');
 
                 if ($foreignRelationName && $relEntity->getRelationParam($foreignRelationName, 'type') === Entity::HAS_ONE) {
-                    $sql = $this->query->createUpdateQuery($entityType, [
-                        'whereClause' => [
-                            'id!=' => $entity->id,
-                            $key => $id,
-                            'deleted' => false,
-                        ],
-                        'update' => [
-                            $key => NULL,
-                        ],
-                    ]);
+                    $sql = $this->queryComposer->compose(
+                        Update::fromRaw([
+                            'from' => $entityType,
+                            'whereClause' => [
+                                'id!=' => $entity->id,
+                                $key => $id,
+                                static::ATTRIBUTE_DELETED => false,
+                            ],
+                            'set' => [
+                                $key => null,
+                            ],
+                        ])
+                    );
 
-                    $this->runQuery($sql, true);
+                    $this->runSql($sql, true);
                 }
 
-                $sql = $this->query->createUpdateQuery($entityType, [
-                    'whereClause' => [
-                        'id' => $entity->id,
-                        'deleted' => false,
-                    ],
-                    'update' => [
-                        $key => $relEntity->id,
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $entityType,
+                        'whereClause' => [
+                            'id' => $entity->id,
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                        'set' => [
+                            $key => $relEntity->id,
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
@@ -778,51 +818,65 @@ abstract class BaseMapper implements Mapper
                 $key = $relationName . 'Id';
                 $typeKey = $relationName . 'Type';
 
-                $sql = $this->query->createUpdateQuery($entityType, [
-                    'whereClause' => [
-                        'id' => $entity->id,
-                        'deleted' => false,
-                    ],
-                    'update' => [
-                        $key => $relEntity->id,
-                        $typeKey => $relEntity->getEntityType(),
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $entityType,
+                        'whereClause' => [
+                            'id' => $entity->id,
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                        'set' => [
+                            $key => $relEntity->id,
+                            $typeKey => $relEntity->getEntityType(),
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
             case Entity::HAS_ONE:
                 $foreignKey = $keySet['foreignKey'];
 
-                if ($this->count($relEntity, ['whereClause' => ['id' => $id]]) === 0) {
+                $selectForCount = Select::fromRaw([
+                    'from' => $relEntity->getEntityType(),
+                    'whereClause' => ['id' => $id],
+                ]);
+
+                if ($this->count($selectForCount) === 0) {
                     return false;
                 }
 
-                $sql = $this->query->createUpdateQuery($relEntity->getEntityType(), [
-                    'whereClause' => [
-                        $foreignKey => $entity->id,
-                        'deleted' => false,
-                    ],
-                    'update' => [
-                        $foreignKey => NULL,
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $relEntity->getEntityType(),
+                        'whereClause' => [
+                            $foreignKey => $entity->id,
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                        'set' => [
+                            $foreignKey => NULL,
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
-                $sql = $this->query->createUpdateQuery($relEntity->getEntityType(), [
-                    'whereClause' => [
-                        'id' => $id,
-                        'deleted' => false,
-                    ],
-                    'update' => [
-                        $foreignKey => $entity->id,
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $relEntity->getEntityType(),
+                        'whereClause' => [
+                            'id' => $id,
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                        'set' => [
+                            $foreignKey => $entity->id,
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
@@ -831,7 +885,12 @@ abstract class BaseMapper implements Mapper
                 $key = $keySet['key'];
                 $foreignKey = $keySet['foreignKey'];
 
-                if ($this->count($relEntity, ['whereClause' => ['id' => $id]]) === 0) {
+                $selectForCount = Select::fromRaw([
+                    'from' => $relEntity->getEntityType(),
+                    'whereClause' => ['id' => $id],
+                ]);
+
+                if ($this->count($selectForCount) === 0) {
                     return false;
                 }
 
@@ -844,15 +903,18 @@ abstract class BaseMapper implements Mapper
                     $set[$foreignType] = $entity->getEntityType();
                 }
 
-                $sql = $this->query->createUpdateQuery($relEntity->getEntityType(), [
-                    'whereClause' => [
-                        'id' => $id,
-                        'deleted' => false,
-                    ],
-                    'update' => $set,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $relEntity->getEntityType(),
+                        'whereClause' => [
+                            'id' => $id,
+                            static::ATTRIBUTE_DELETED => false,
+                        ],
+                        'set' => $set,
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
@@ -860,7 +922,12 @@ abstract class BaseMapper implements Mapper
                 $nearKey = $keySet['nearKey'];
                 $distantKey = $keySet['distantKey'];
 
-                if ($this->count($relEntity, ['whereClause' => ['id' => $id]]) === 0) {
+                $selectForCount = Select::fromRaw([
+                    'from' => $relEntity->getEntityType(),
+                    'whereClause' => ['id' => $id],
+                ]);
+
+                if ($this->count($selectForCount) === 0) {
                     return false;
                 }
 
@@ -882,11 +949,14 @@ abstract class BaseMapper implements Mapper
                     $where[$f] = $v;
                 }
 
-                $sql = $this->query->createSelectQuery($middleName, [
-                    'select' => ['id'],
-                    'whereClause' => $where,
-                    'withDeleted' => true,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Select::fromRaw([
+                        'from' => $middleName,
+                        'select' => ['id'],
+                        'whereClause' => $where,
+                        'withDeleted' => true,
+                    ])
+                );
 
                 $ps = $this->pdo->query($sql);
 
@@ -897,7 +967,7 @@ abstract class BaseMapper implements Mapper
                     $columns = array_keys($values);
 
                     $update = [
-                        'deleted' => false,
+                        static::ATTRIBUTE_DELETED => false,
                     ];
 
                     foreach ($data as $column => $value) {
@@ -906,31 +976,37 @@ abstract class BaseMapper implements Mapper
                         $update[$column] = $value;
                     }
 
-                    $sql = $this->query->createInsertQuery($middleName, [
-                        'columns' => $columns,
-                        'values' => $values,
-                        'update' => $update,
-                    ]);
+                    $sql = $this->queryComposer->compose(
+                        Insert::fromRaw([
+                            'into' => $middleName,
+                            'columns' => $columns,
+                            'values' => $values,
+                            'updateSet' => $update,
+                        ])
+                    );
 
-                    $this->runQuery($sql, true);
+                    $this->runSql($sql, true);
 
                     return true;
                 }
 
                 $update = [
-                    'deleted' => false,
+                    static::ATTRIBUTE_DELETED => false,
                 ];
 
                 foreach ($data as $column => $value) {
                     $update[$column] = $value;
                 }
 
-                $sql = $this->query->createUpdateQuery($middleName, [
-                    'whereClause' => $where,
-                    'update' => $update,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $middleName,
+                        'whereClause' => $where,
+                        'set' => $update,
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
         }
@@ -1007,14 +1083,17 @@ abstract class BaseMapper implements Mapper
                     }
                 }
 
-                $where['deleted'] = false;
+                $where[static::ATTRIBUTE_DELETED] = false;
 
-                $sql = $this->query->createUpdateQuery($entityType, [
-                    'whereClause' => $where,
-                    'update' => $update,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $entityType,
+                        'whereClause' => $where,
+                        'set' => $update,
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
@@ -1041,14 +1120,17 @@ abstract class BaseMapper implements Mapper
                     $update[$foreignType] = null;
                 }
 
-                $where['deleted'] = false;
+                $where[static::ATTRIBUTE_DELETED] = false;
 
-                $sql = $this->query->createUpdateQuery($relEntity->getEntityType(), [
-                    'whereClause' => $where,
-                    'update' => $update,
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $relEntity->getEntityType(),
+                        'whereClause' => $where,
+                        'set' => $update,
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
 
@@ -1076,14 +1158,17 @@ abstract class BaseMapper implements Mapper
                     $where[$f] = $v;
                 }
 
-                $sql = $this->query->createUpdateQuery($middleName, [
-                    'whereClause' => $where,
-                    'update' => [
-                        'deleted' => true,
-                    ],
-                ]);
+                $sql = $this->queryComposer->compose(
+                    Update::fromRaw([
+                        'from' => $middleName,
+                        'whereClause' => $where,
+                        'set' => [
+                            static::ATTRIBUTE_DELETED => true,
+                        ],
+                    ])
+                );
 
-                $this->runQuery($sql, true);
+                $this->runSql($sql, true);
 
                 return true;
         }
@@ -1117,13 +1202,16 @@ abstract class BaseMapper implements Mapper
             $update = $onDuplicateSetMap = $this->getInsertOnDuplicateSetMap($entity, $onDuplicateUpdateAttributeList);
         }
 
-        $sql = $this->query->createInsertQuery($entity->getEntityType(), [
-            'columns' => $this->getInsertColumnList($entity),
-            'values' => $this->getInsertValueMap($entity),
-            'update' => $update,
-        ]);
+        $sql = $this->queryComposer->compose(
+            Insert::fromRaw([
+                'into' => $entity->getEntityType(),
+                'columns' => $this->getInsertColumnList($entity),
+                'values' => $this->getInsertValueMap($entity),
+                'updateSet' => $update,
+            ])
+        );
 
-        $this->runQuery($sql, true);
+        $this->runSql($sql, true);
     }
 
     /**
@@ -1141,12 +1229,15 @@ abstract class BaseMapper implements Mapper
             $values[] = $this->getInsertValueMap($entity);
         }
 
-        $sql = $this->query->createInsertQuery($entity->getEntityType(), [
-            'columns' => $this->getInsertColumnList($collection[0]),
-            'values' => $values,
-        ]);
+        $sql = $this->queryComposer->compose(
+            Insert::fromRaw([
+                'into' => $entity->getEntityType(),
+                'columns' => $this->getInsertColumnList($collection[0]),
+                'values' => $values,
+            ])
+        );
 
-        $this->runQuery($sql, true);
+        $this->runSql($sql, true);
     }
 
     protected function getInsertColumnList(Entity $entity) : array
@@ -1221,13 +1312,16 @@ abstract class BaseMapper implements Mapper
             return;
         }
 
-        $sql = $this->query->createUpdateQuery($entity->getEntityType(), [
-            'whereClause' => [
-                'id' => $entity->id,
-                'deleted' => false,
-            ],
-            'update' => $valueMap,
-        ]);
+        $sql = $this->queryComposer->compose(
+            Update::fromRaw([
+                'from' => $entity->getEntityType(),
+                'whereClause' => [
+                    'id' => $entity->id,
+                    static::ATTRIBUTE_DELETED => false,
+                ],
+                'set' => $valueMap,
+            ])
+        );
 
         $this->pdo->query($sql);
     }
@@ -1261,14 +1355,15 @@ abstract class BaseMapper implements Mapper
         ];
 
         if ($onlyDeleted) {
-            $whereClause['deleted'] = true;
+            $whereClause[static::ATTRIBUTE_DELETED] = true;
         }
 
-        $sql = $this->query->createDeleteQuery($entityType, [
+        $sql = $this->queryComposer->compose(Delete::fromRaw([
+            'from' => $entityType,
             'whereClause' => $whereClause,
-        ]);
+        ]));
 
-        $this->runQuery($sql);
+        $this->runSql($sql);
     }
 
     /**
@@ -1284,12 +1379,15 @@ abstract class BaseMapper implements Mapper
             'id' => $id,
         ];
 
-        $sql = $this->query->createUpdateQuery($entityType, [
-            'whereClause' => $whereClause,
-            'update' => ['deleted' => false],
-        ]);
+        $sql = $this->queryComposer->compose(
+            Update::fromRaw([
+                'from' => $entityType,
+                'whereClause' => $whereClause,
+                'set' => [static::ATTRIBUTE_DELETED => false],
+            ])
+        );
 
-        $this->runQuery($sql);
+        $this->runSql($sql);
     }
 
     /**
@@ -1297,7 +1395,7 @@ abstract class BaseMapper implements Mapper
      */
     public function delete(Entity $entity) : bool
     {
-        $entity->set('deleted', true);
+        $entity->set(static::ATTRIBUTE_DELETED, true);
 
         return (booL) $this->update($entity);
     }
@@ -1315,9 +1413,15 @@ abstract class BaseMapper implements Mapper
                         !empty($defs['autoincrement'])
                         ||
                         isset($defs['source']) && $defs['source'] != 'db'
-                    ) continue;
-                    if ($defs['type'] == Entity::FOREIGN) continue;
+                    ) {
+                        continue;
+                    }
+
+                    if ($defs['type'] == Entity::FOREIGN) {
+                        continue;
+                    }
                 }
+
                 $data[$attribute] = $entity->get($attribute);
             }
         }
@@ -1325,11 +1429,9 @@ abstract class BaseMapper implements Mapper
         return $data;
     }
 
-    protected function fromRow(Entity $entity, $data) : Entity
+    protected function populateEntityFromRow(Entity $entity, $data)
     {
         $entity->set($data);
-
-        return $entity;
     }
 
     protected function getManyManyJoin(Entity $entity, string $relationName, ?array $conditions = null) : array
@@ -1357,7 +1459,7 @@ abstract class BaseMapper implements Mapper
             [
                 "{$distantKey}:" => $foreignKey,
                 "{$nearKey}" => $entity->get($key),
-                "deleted" => false,
+                static::ATTRIBUTE_DELETED => false,
             ],
         ];
 
diff --git a/application/Espo/ORM/DB/Helper.php b/application/Espo/ORM/Mapper/Helper.php
similarity index 99%
rename from application/Espo/ORM/DB/Helper.php
rename to application/Espo/ORM/Mapper/Helper.php
index c66ea4f425..82f20b37bb 100644
--- a/application/Espo/ORM/DB/Helper.php
+++ b/application/Espo/ORM/Mapper/Helper.php
@@ -27,7 +27,7 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB;
+namespace Espo\ORM\Mapper;
 
 use Espo\ORM\{
     Entity,
diff --git a/application/Espo/ORM/DB/Mapper.php b/application/Espo/ORM/Mapper/Mapper.php
similarity index 86%
rename from application/Espo/ORM/DB/Mapper.php
rename to application/Espo/ORM/Mapper/Mapper.php
index 314de34542..9cd8d5c00e 100644
--- a/application/Espo/ORM/DB/Mapper.php
+++ b/application/Espo/ORM/Mapper/Mapper.php
@@ -27,45 +27,46 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB;
+namespace Espo\ORM\Mapper;
 
 use Espo\ORM\{
     Entity,
     Collection,
+    QueryParams\Select,
 };
 
 interface Mapper
 {
     /**
-     * Select an entity by ID.
+     * Get the first entity from DB.
      */
-    public function selectById(Entity $entity, string $id, ?array $params = null) : ?Entity;
+    public function selectOne(Select $select) : ?Entity;
 
     /**
      * Select a list of entities according to given parameters.
      */
-    public function select(Entity $entity, ?array $params = null) : Collection;
+    public function select(Select $select) : Collection;
 
     /**
      * Returns count of records according to given parameters.
      *
      * @return Record count.
      */
-    public function count(Entity $entity, ?array $params = null) : int;
+    public function count(Select $select) : int;
 
     /**
      * Selects related entity or list of entities.
      *
      * @return List of entities or one entity.
      */
-    public function selectRelated(Entity $entity, string $relationName, ?array $params = null);
+    public function selectRelated(Entity $entity, string $relationName, ?Select $select = null);
 
     /**
      * Returns count of related records according to given parameters.
      *
      * @return A number of records.
      */
-    public function countRelated(Entity $entity, string $relationName, ?array $params = null) : int;
+    public function countRelated(Entity $entity, string $relationName, ?Select $select = null) : int;
 
     /**
      * Insert an entity into DB.
diff --git a/application/Espo/ORM/DB/MysqlMapper.php b/application/Espo/ORM/Mapper/MysqlMapper.php
similarity index 98%
rename from application/Espo/ORM/DB/MysqlMapper.php
rename to application/Espo/ORM/Mapper/MysqlMapper.php
index 64067774c5..a087df7e3e 100644
--- a/application/Espo/ORM/DB/MysqlMapper.php
+++ b/application/Espo/ORM/Mapper/MysqlMapper.php
@@ -27,7 +27,7 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB;
+namespace Espo\ORM\Mapper;
 
 class MysqlMapper extends BaseMapper
 {
diff --git a/application/Espo/ORM/Metadata.php b/application/Espo/ORM/Metadata.php
index 6f002501db..5d6f7c4799 100644
--- a/application/Espo/ORM/Metadata.php
+++ b/application/Espo/ORM/Metadata.php
@@ -29,8 +29,11 @@
 
 namespace Espo\ORM;
 
-use Espo\Core\Utils\Util;
+use InvalidArgumentException;
 
+/**
+ * Metadata of all entities.
+ */
 class Metadata
 {
     protected $data;
@@ -50,13 +53,17 @@ class Metadata
      */
     public function get(string $entityType, $key = null, $default = null)
     {
-        if (!array_key_exists($entityType, $this->data)) {
+        if (!$this->has($entityType)) {
             return null;
         }
-        $data = $this->data[$entityType];
-        if (!$key) return $data;
 
-        return Util::getValueByKey($data, $key, $default);
+        $data = $this->data[$entityType];
+
+        if ($key === null) {
+            return $data;
+        }
+
+        return self::getValueByKey($data, $key, $default);
     }
 
     /**
@@ -64,9 +71,39 @@ class Metadata
      */
     public function has(string $entityType) : bool
     {
-        if (!array_key_exists($entityType, $this->data)) {
-            return false;
+        return array_key_exists($entityType, $this->data);
+    }
+
+    private static function getValueByKey(array $data, $key = null, $default = null)
+    {
+        if (!is_string($key) && !is_array($key) && !is_null($key)) {
+            throw new InvalidArgumentException();
         }
-        return true;
+
+        if (is_null($key) || empty($key)) {
+            return $data;
+        }
+
+        if (!is_string($key) && !is_array($key)) {
+            throw new InvalidArgumentException();
+        }
+
+        $path = $key;
+
+        if (is_string($key)) {
+            $path = explode('.', $key);
+        }
+
+        $item = $data;
+
+        foreach ($path as $k) {
+            if (!array_key_exists($k, $item)) {
+                return $default;
+            }
+
+            $item = $item[$k];
+        }
+
+        return $item;
     }
 }
diff --git a/application/Espo/ORM/QueryBuilder.php b/application/Espo/ORM/QueryBuilder.php
new file mode 100644
index 0000000000..6afb3775d0
--- /dev/null
+++ b/application/Espo/ORM/QueryBuilder.php
@@ -0,0 +1,100 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM;
+
+use Espo\ORM\{
+    QueryParams\SelectBuilder,
+    QueryParams\UpdateBuilder,
+    QueryParams\DeleteBuilder,
+    QueryParams\InsertBuilder,
+    QueryParams\Query,
+    QueryParams\Builder,
+};
+
+use ReflectionClass;
+use RuntimeException;
+
+/**
+ * Creates query builders for specific query types.
+ */
+class QueryBuilder
+{
+    public function __construct()
+    {
+    }
+
+    /**
+     * Proceed with SELECT builder.
+     */
+    public function select() : SelectBuilder
+    {
+        return new SelectBuilder();
+    }
+
+    /**
+     * Proceed with UPDATE builder.
+     */
+    public function update() : UpdateBuilder
+    {
+        return new UpdateBuilder();
+    }
+
+    /**
+     * Proceed with DELETE builder.
+     */
+    public function delete() : DeleteBuilder
+    {
+        return new DeleteBuilder();
+    }
+
+    /**
+     * Proceed with INSERT builder.
+     */
+    public function insert() : InsertBuilder
+    {
+        return new InsertBuilder();
+    }
+
+    /**
+     * Cone an existing query and proceed modifying it.
+     */
+    public function clone(Query $query) : Builder
+    {
+        $class = new ReflectionClass($query);
+
+        $methodName = ucfirst($class->getShortName());
+
+        if (!method_exists($this, $methodName)) {
+            throw new RuntimeException("Can't clone an unsupported query.");
+        }
+
+        return $this->$methodName()->clone($query);
+    }
+}
diff --git a/application/Espo/ORM/DB/Query/BaseQuery.php b/application/Espo/ORM/QueryComposer/BaseQueryComposer.php
similarity index 87%
rename from application/Espo/ORM/DB/Query/BaseQuery.php
rename to application/Espo/ORM/QueryComposer/BaseQueryComposer.php
index 11763f5c96..eef8accc63 100644
--- a/application/Espo/ORM/DB/Query/BaseQuery.php
+++ b/application/Espo/ORM/QueryComposer/BaseQueryComposer.php
@@ -27,23 +27,31 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB\Query;
+namespace Espo\ORM\QueryComposer;
 
 use Espo\ORM\{
     Entity,
     EntityFactory,
     Metadata,
-    DB\Helper,
-    DB\Query\Functions,
+    Mapper\Helper,
+    QueryParams\Query as Query,
+    QueryParams\Select as SelectQuery,
+    QueryParams\Update as UpdateQuery,
+    QueryParams\Insert as InsertQuery,
+    QueryParams\Delete as DeleteQuery,
 };
 
 use PDO;
 use RuntimeException;
+use LogicException;
 
 /**
  * Composes SQL queries.
+ *
+ * @todo Add method that wraps into ``.
+ * @todo Break into sub-classes. Put sub-classes into `\Parts` namespace.
  */
-abstract class BaseQuery
+abstract class BaseQueryComposer implements QueryComposer
 {
     protected static $paramList = [
         'select',
@@ -67,7 +75,7 @@ abstract class BaseQuery
         'maxTextColumnsLength',
         'useIndex',
         'withDeleted',
-        'update',
+        'set',
     ];
 
     protected static $sqlOperators = [
@@ -162,24 +170,76 @@ abstract class BaseQuery
     }
 
     /**
-     * Compose a SELECT query.
+     * {@inheritdoc}
      */
-    public function createSelectQuery(string $entityType, ?array $params = nul) : string
+    public function compose(Query $query) : string
     {
-        $params = $params ?? [];
+        if ($query instanceof SelectQuery) {
+            return $this->composeSelect($query);
+        }
 
-        return $this->createSelectQueryInternal($entityType, $params);
+        if ($query instanceof UpdateQuery) {
+            return $this->composeUpdate($query);
+        }
+
+        if ($query instanceof InsertQuery) {
+            return $this->composeInsert($query);
+        }
+
+        if ($query instanceof DeleteQuery) {
+            return $this->composeDelete($query);
+        }
+
+        throw new RuntimeException("ORM Query: Query params could not be handled.");
+    }
+
+    protected function composeSelect(SelectQuery $queryParam) : string
+    {
+        $params = $queryParam->getRawParams();
+
+        return $this->createSelectQueryInternal($params);
+    }
+
+    protected function composeUpdate(UpdateQuery $queryParam) : string
+    {
+        $params = $queryParam->getRawParams();
+
+        return $this->createUpdateQuery($params);
+    }
+
+    protected function composeDelete(DeleteQuery $queryParam) : string
+    {
+        $params = $queryParam->getRawParams();
+
+        return $this->createDeleteQuery($params);
+    }
+
+    protected function composeInsert(InsertQuery $queryParam) : string
+    {
+        $params = $queryParam->getRawParams();
+
+        return $this->createInsertQuery($params);
     }
 
     /**
-     * Compose a DELETE query.
+     * @deprecated
+     * @todo Remove in v6.4.
      */
-    public function createDeleteQuery(string $entityType, ?array $params = null) : string
+    public function createSelectQuery(string $entityType, ?array $params = null) : string
     {
         $params = $params ?? [];
 
+        $params['from'] = $entityType;
+
+        return $this->compose(SelectQuery::fromRaw($params));
+    }
+
+    protected function createDeleteQuery(array $params = null) : string
+    {
         $params = $this->normilizeParams(self::DELETE_METHOD, $params);
 
+        $entityType = $params['from'];
+
         $entity = $this->getSeed($entityType);
 
         $wherePart = $this->getWherePart($entity, $params['whereClause'], 'AND', $params);
@@ -197,16 +257,13 @@ abstract class BaseQuery
         return $sql;
     }
 
-    /**
-     * Compose an UPDATE query.
-     */
-    public function createUpdateQuery(string $entityType, ?array $params = null) : string
+    protected function createUpdateQuery(array $params = null) : string
     {
-        $params = $params ?? [];
-
         $params = $this->normilizeParams(self::UPDATE_METHOD, $params);
 
-        $values = $params['update'];
+        $entityType = $params['from'];
+
+        $values = $params['set'];
 
         $entity = $this->getSeed($entityType);
 
@@ -228,13 +285,15 @@ abstract class BaseQuery
         return $sql;
     }
 
-    public function createInsertQuery(string $entityType, array $params) : string
+    protected function createInsertQuery(array $params) : string
     {
         $params = $this->normilizeInsertParams($params);
 
+        $entityType = $params['into'];
+
         $columns = $params['columns'];
         $values = $params['values'];
-        $update = $params['update'];
+        $updateSet = $params['updateSet'];
         $valuesSelectParams = $params['valuesSelectParams'];
 
         $columnsPart = $this->getInsertColumnsPart($columns);
@@ -243,8 +302,8 @@ abstract class BaseQuery
 
         $updatePart = null;
 
-        if ($update) {
-            $updatePart = $this->getInsertUpdatePart($update);
+        if ($updateSet) {
+            $updatePart = $this->getInsertUpdatePart($updateSet);
         }
 
         return $this->composeInsertQuery($this->toDb($entityType), $columnsPart, $valuesPart, $updatePart);
@@ -330,10 +389,10 @@ abstract class BaseQuery
             }
         }
 
-        $update = $params['update'] = $params['update'] ?? null;
+        $updateSet = $params['updateSet'] = $params['updateSet'] ?? null;
 
-        if ($update && !is_array($update)) {
-            throw new RuntimeException("ORM Query: Bad 'update' param.");
+        if ($updateSet && !is_array($updateSet)) {
+            throw new RuntimeException("ORM Query: Bad 'updateSet' param.");
         }
 
         return $params;
@@ -365,24 +424,26 @@ abstract class BaseQuery
         }
 
         if ($method !== self::UPDATE_METHOD) {
-            if (isset($params['update'])) {
-                 throw new RuntimeException("ORM Query: Param 'update' is not allowed for '{$method}'.");
+            if (isset($params['set'])) {
+                throw new RuntimeException("ORM Query: Param 'set' is not allowed for '{$method}'.");
             }
         }
 
-        if (isset($params['update']) && !is_array($params['update'])) {
-            throw new RuntimeException("ORM Query: Param 'update' should be an array.");
+        if (isset($params['set']) && !is_array($params['set'])) {
+            throw new RuntimeException("ORM Query: Param 'set' should be an array.");
         }
 
         return $params;
     }
 
-    protected function createSelectQueryInternal(string $entityType, ?array $params = null) : string
+    protected function createSelectQueryInternal(array $params = null) : string
     {
-        $entity = $this->getSeed($entityType);
-
         $params = $this->normilizeParams(self::SELECT_METHOD, $params);
 
+        $entityType = $params['from'];
+
+        $entity = $this->getSeed($entityType);
+
         $isAggregation = (bool) ($params['aggregation'] ?? null);
 
         $whereClause = $params['whereClause'] ?? [];
@@ -405,9 +466,7 @@ abstract class BaseQuery
         }
 
         if (!$isAggregation) {
-            $selectPart = $this->getSelectPart(
-                $entity, $params['select'], $params['distinct'], $params['skipTextColumns'], $params['maxTextColumnsLength'], $params
-            );
+            $selectPart = $this->getSelectPart($entity, $params);
 
             $orderPart = $this->getOrderPart($entity, $params['orderBy'], $params['order'], $params);
 
@@ -579,26 +638,14 @@ abstract class BaseQuery
                 }
             }
             if (count($extraSelect)) {
-                $extraSelectPart = $this->getSelectPart(
-                    $entity, $extraSelect, false
-                );
+                $extraSelectPart = $this->getSelectPart($entity, ['select' => $extraSelect]);
+
                 if ($extraSelectPart) {
                     $selectPart .= ', ' . $extraSelectPart;
                 }
             }
         }
 
-        if (
-            !empty($params['additionalColumns']) && is_array($params['additionalColumns']) && !empty($params['relationName'])
-        ) {
-            $alias = $this->sanitizeSelectAlias(lcfirst($params['relationName']));
-
-            foreach ($params['additionalColumns'] as $column => $field) {
-                $itemAlias = $this->sanitizeSelectAlias($field);
-                $selectPart .= ", " . $alias . "." . $this->toDb($this->sanitize($column)) . " AS `{$itemAlias}`";
-            }
-        }
-
         if (!empty($params['additionalSelectColumns']) && is_array($params['additionalSelectColumns'])) {
             foreach ($params['additionalSelectColumns'] as $column => $field) {
                 $itemAlias = $this->sanitizeSelectAlias($field);
@@ -623,7 +670,7 @@ abstract class BaseQuery
         if (strpos($function, 'YEAR_') === 0 && $function !== 'YEAR_NUMBER') {
             $fiscalShift = substr($function, 5);
             if (is_numeric($fiscalShift)) {
-                $fiscalShift = intval($fiscalShift);
+                $fiscalShift = (int) $fiscalShift;
                 $fiscalFirstMonth = $fiscalShift + 1;
 
                 return
@@ -636,7 +683,7 @@ abstract class BaseQuery
         if (strpos($function, 'QUARTER_') === 0 && $function !== 'QUARTER_NUMBER') {
             $fiscalShift = substr($function, 8);
             if (is_numeric($fiscalShift)) {
-                $fiscalShift = intval($fiscalShift);
+                $fiscalShift = (int) $fiscalShift;
                 $fiscalFirstMonth = $fiscalShift + 1;
                 $fiscalDistractedMonth = 12 - $fiscalFirstMonth;
 
@@ -694,10 +741,12 @@ abstract class BaseQuery
             case 'DAY':
                 return "DATE_FORMAT({$part}, '%Y-%m-%d')";
             case 'WEEK_0':
-                return "CONCAT(SUBSTRING(YEARWEEK({$part}, 6), 1, 4), '/', TRIM(LEADING '0' FROM SUBSTRING(YEARWEEK({$part}, 6), 5, 2)))";
+                return "CONCAT(SUBSTRING(YEARWEEK({$part}, 6), 1, 4), '/', ".
+                "TRIM(LEADING '0' FROM SUBSTRING(YEARWEEK({$part}, 6), 5, 2)))";
             case 'WEEK':
             case 'WEEK_1':
-                return "CONCAT(SUBSTRING(YEARWEEK({$part}, 3), 1, 4), '/', TRIM(LEADING '0' FROM SUBSTRING(YEARWEEK({$part}, 3), 5, 2)))";
+                return "CONCAT(SUBSTRING(YEARWEEK({$part}, 3), 1, 4), '/', ".
+                "TRIM(LEADING '0' FROM SUBSTRING(YEARWEEK({$part}, 3), 5, 2)))";
             case 'QUARTER':
                 return "CONCAT(YEAR({$part}), '_', QUARTER({$part}))";
             case 'MONTH_NUMBER':
@@ -763,7 +812,7 @@ abstract class BaseQuery
             $offsetHoursString = substr($offsetHoursString, 1, -1);
         }
         $offset = floatval($offsetHoursString);
-        $offsetHours = intval(floor(abs($offset)));
+        $offsetHours = (int) (floor(abs($offset)));
         $offsetMinutes = (abs($offset) - $offsetHours) * 60;
         $offsetString =
             str_pad((string) $offsetHours, 2, '0', \STR_PAD_LEFT) .
@@ -857,6 +906,7 @@ abstract class BaseQuery
                 $attribute = substr($attribute, 1, -1);
             }
         }
+
         if (!empty($function)) {
             $function = strtoupper($this->sanitize($function));
         }
@@ -866,12 +916,13 @@ abstract class BaseQuery
         if ($function && in_array($function, Functions::$multipleArgumentsFunctionList)) {
             $arguments = $attribute;
 
-            $argumentList = $this->parseArgumentListFromFunctionContent($arguments);
+            $argumentList = self::parseArgumentListFromFunctionContent($arguments);
 
             $argumentPartList = [];
             foreach ($argumentList as $argument) {
                 $argumentPartList[] = $this->getFunctionArgumentPart($entity, $argument, $distinct, $params);
             }
+
             $part = implode(', ', $argumentPartList);
 
         } else {
@@ -890,8 +941,9 @@ abstract class BaseQuery
         return self::getAllAttributesFromComplexExpressionImplementation($expression);
     }
 
-    protected static function getAllAttributesFromComplexExpressionImplementation(string $expression, ?array &$list = null) : array
-    {
+    protected static function getAllAttributesFromComplexExpressionImplementation(
+        string $expression, ?array &$list = null
+    ) : array {
         if (!$list) $list = [];
 
         $arguments = $expression;
@@ -1117,6 +1169,7 @@ abstract class BaseQuery
                     $params['leftJoins'][] = $j;
                 }
             }
+
             if (!empty($fieldDefs[$type]['joins'])) {
                 foreach ($fieldDefs[$type]['joins'] as $j) {
                     $jAlias = $this->obtainJoinAlias($j);
@@ -1132,11 +1185,14 @@ abstract class BaseQuery
                 }
             }
 
+            // Some fields may need additional select items add to a query.
             if (!empty($fieldDefs[$type]['additionalSelect'])) {
                 $params['extraAdditionalSelect'] = $params['extraAdditionalSelect'] ?? [];
+
                 foreach ($fieldDefs[$type]['additionalSelect'] as $value) {
                     $value = str_replace('{alias}', $alias, $value);
                     $value = str_replace('{attribute}', $attribute, $value);
+
                     if (!in_array($value, $params['extraAdditionalSelect'])) {
                         $params['extraAdditionalSelect'][] = $value;
                     }
@@ -1147,115 +1203,170 @@ abstract class BaseQuery
         return $part;
     }
 
-    protected function getSelectPart(
-        Entity $entity,
-        ?array $itemList = null,
-        bool $distinct = false,
-        bool $skipTextColumns = false,
-        ?int $maxTextColumnsLength = null,
-        ?array &$params = null
-    ) : string {
-        $select = '';
-        $arr = [];
-        $specifiedList = is_array($itemList) ? true : false;
+    protected function getSelectPart(Entity $entity, array &$params) : string
+    {
+        $params = $params ?? [];
 
-        if (empty($itemList)) {
-            $attributeList = $entity->getAttributeList();
-        } else {
-            $attributeList = $itemList;
+        $itemList = $params['select'] ?? [];
+
+        $noSelectSpecified = !count($itemList);
+
+        if (!$noSelectSpecified && $itemList[0] === '*') {
+            array_shift($itemList);
+
+            foreach (array_reverse($entity->getAttributeList()) as $item) {
+                array_unshift($itemList, $item);
+            }
         }
 
-        if ($params && isset($params['additionalSelect'])) {
+        if ($noSelectSpecified) {
+            $itemList = $entity->getAttributeList();
+        }
+
+        // @todo Get rid of 'additionalSelect' parameter.
+        if (isset($params['additionalSelect'])) {
             foreach ($params['additionalSelect'] as $item) {
-                $attributeList[] = $item;
+                $itemList[] = $item;
             }
         }
 
-        foreach ($attributeList as $i => $attribute) {
-            if (is_string($attribute)) {
-                if (strpos($attribute, ':')) {
-                    $attributeList[$i] = [
-                        $attribute,
-                        $attribute
-                    ];
+        foreach ($itemList as $i => $item) {
+            if (is_string($item)) {
+                if (strpos($item, ':')) {
+                    $itemList[$i] = [$item, $item];
                     continue;
                 }
+                continue;
             }
         }
 
-        foreach ($attributeList as $attribute) {
-            $attributeType = null;
-            if (is_string($attribute)) {
-                $attributeType = $entity->getAttributeType($attribute);
-            }
-            if ($skipTextColumns) {
-                if ($attributeType === $entity::TEXT) {
-                    continue;
-                }
+        $itemPairList = [];
+
+        foreach ($itemList as $item) {
+            $pair = $this->getSelectPartItemPair($entity, $params, $item);
+
+            if ($pair === null) {
+                continue;
             }
 
-            if (is_array($attribute) && count($attribute) == 2) {
-                if (stripos($attribute[0], 'VALUE:') === 0) {
-                    $part = substr($attribute[0], 6);
-                    if ($part !== false) {
-                        $part = $this->quote($part);
-                    } else {
-                        $part = $this->quote('');
-                    }
+            $itemPairList[] = $pair;
+        }
+
+        if (!count($itemPairList)) {
+            throw new RuntimeException("ORM Query: Select part can't be empty.");
+        }
+
+        $selectPartItemList = [];
+
+        foreach ($itemPairList as $item) {
+            $expression = $item[0];
+            $alias = $this->sanitizeSelectAlias($item[1]);
+
+            if ($expression === '' || $alias === '') {
+                throw new RuntimeException("Bad select expression.");
+            }
+
+            $selectPartItemList[] = "{$expression} AS `{$alias}`";
+        }
+
+        $selectPart = implode(', ', $selectPartItemList);
+
+        return $selectPart;
+    }
+
+    protected function getSelectPartItemPair(Entity $entity, array &$params, $attribute) : ?array
+    {
+        $maxTextColumnsLength = $params['maxTextColumnsLength'] ?? null;
+        $skipTextColumns = $params['skipTextColumns'] ?? false;
+        $distinct = $params['distinct'] ?? false;
+
+        $attributeType = null;
+
+        if (!is_array($attribute) && !is_string($attribute)) {
+            throw new RuntimeException("ORM Query: Bad select item.");
+        }
+
+        if (is_string($attribute)) {
+            $attributeType = $entity->getAttributeType($attribute);
+        }
+
+        if ($skipTextColumns) {
+            if ($attributeType === $entity::TEXT) {
+                return null;
+            }
+        }
+
+        if (is_array($attribute) && count($attribute) == 2) {
+            $alias = $attribute[1];
+
+            if (stripos($attribute[0], 'VALUE:') === 0) {
+                $part = substr($attribute[0], 6);
+
+                if ($part !== false) {
+                    $part = $this->quote($part);
                 } else {
-                    if (!$entity->hasAttribute($attribute[0])) {
-                        $part = $this->convertComplexExpression($entity, $attribute[0], $distinct, $params);
-                    } else {
-                        $fieldDefs = $entity->getAttributes()[$attribute[0]];
-                        if (!empty($fieldDefs['select'])) {
-                            $part = $this->getAttributeSql($entity, $attribute[0], 'select', $params);
-                        } else {
-                            if (!empty($fieldDefs['noSelect'])) {
-                                continue;
-                            }
-                            if (!empty($fieldDefs['notStorable'])) {
-                                continue;
-                            }
-                            $part = $this->getFieldPath($entity, $attribute[0], $params);
-                        }
-                    }
+                    $part = $this->quote('');
                 }
 
-                $arr[] = $part . ' AS `' . $this->sanitizeSelectAlias($attribute[1]) . '`';
-                continue;
+                return [$part, $alias];
             }
 
-            $attribute = $this->sanitizeSelectItem($attribute);
+            if (!$entity->hasAttribute($attribute[0])) {
+                $part = $this->convertComplexExpression($entity, $attribute[0], $distinct, $params);
 
-            if ($entity->hasAttribute($attribute)) {
-                $fieldDefs = $entity->getAttributes()[$attribute];
-            } else {
-                $part = $this->convertComplexExpression($entity, $attribute, $distinct, $params);
-                $arr[] = $part . ' AS `' . $this->sanitizeSelectAlias($attribute) . '`';
-                continue;
+                return [$part, $alias];
             }
 
+            $fieldDefs = $entity->getAttributes()[$attribute[0]];
+
             if (!empty($fieldDefs['select'])) {
-                $fieldPath = $this->getAttributeSql($entity, $attribute, 'select', $params);
-            } else {
-                if (!empty($fieldDefs['notStorable']) && ($fieldDefs['type'] ?? null) !== 'foreign') {
-                    continue;
-                }
-                if ($attributeType === null) {
-                    continue;
-                }
-                $fieldPath = $this->getFieldPath($entity, $attribute, $params);
-                if ($attributeType === $entity::TEXT && $maxTextColumnsLength !== null) {
-                    $fieldPath = 'LEFT(' . $fieldPath . ', '. intval($maxTextColumnsLength) . ')';
-                }
+                $part = $this->getAttributeSql($entity, $attribute[0], 'select', $params);
+
+                return [$part, $alias];
             }
 
-            $arr[] = $fieldPath . ' AS `' . $attribute . '`';
+            if (!empty($fieldDefs['noSelect'])) {
+                return null;
+            }
+
+            if (!empty($fieldDefs['notStorable'])) {
+                return null;
+            }
+
+            $part = $this->getAttributePath($entity, $attribute[0], $params);
+
+            return [$part, $alias];
         }
 
-        $select = implode(', ', $arr);
+        if (!$entity->hasAttribute($attribute)) {
+            $expression = $this->sanitizeSelectItem($attribute);
 
-        return $select;
+            $part = $this->convertComplexExpression($entity, $expression, $distinct, $params);
+
+            return [$part, $attribute];
+        }
+
+        if ($entity->getAttributeParam($attribute, 'select')) {
+            $fieldPath = $this->getAttributeSql($entity, $attribute, 'select', $params);
+
+            return [$fieldPath, $attribute];
+        }
+
+        if ($attributeType === null) {
+            return null;
+        }
+
+        if ($entity->getAttributeParam($attribute, 'notStorable') && $attributeType !== Entity::FOREIGN) {
+            return null;
+        }
+
+        $fieldPath = $this->getAttributePath($entity, $attribute, $params);
+
+        if ($attributeType === Entity::TEXT && $maxTextColumnsLength !== null) {
+            $fieldPath = 'LEFT(' . $fieldPath . ', '. strval($maxTextColumnsLength) . ')';
+        }
+
+        return [$fieldPath, $attribute];
     }
 
     protected function getBelongsToJoinItemPart(Entity $entity, $relationName, $r = null, $alias = null)
@@ -1276,7 +1387,8 @@ abstract class BaseQuery
 
         if ($alias) {
             return "JOIN `" . $this->toDb($r['entity']) . "` AS `" . $alias . "` ON ".
-                   $this->toDb($entity->getEntityType()) . "." . $this->toDb($key) . " = " . $alias . "." . $this->toDb($foreignKey);
+                   $this->toDb($entity->getEntityType()) . "." . $this->toDb($key) . " = " .
+                   $alias . "." . $this->toDb($foreignKey);
         }
     }
 
@@ -1362,7 +1474,7 @@ abstract class BaseQuery
             if ($useColumnAlias) {
                 $fieldPath = '`'. $this->sanitizeSelectAlias($field) . '`';
             } else {
-                $fieldPath = $this->getFieldPathForOrderBy($entity, $field, $params);
+                $fieldPath = $this->getAttributePathForOrderBy($entity, $field, $params);
             }
             $listQuoted = [];
             $list = array_reverse(explode(',', $list));
@@ -1403,7 +1515,7 @@ abstract class BaseQuery
         if ($useColumnAlias) {
             $fieldPath = '`'. $this->sanitizeSelectAlias($orderBy) . '`';
         } else {
-            $fieldPath = $this->getFieldPathForOrderBy($entity, $orderBy, $params);
+            $fieldPath = $this->getAttributePathForOrderBy($entity, $orderBy, $params);
         }
 
         return "{$fieldPath} " . $order;
@@ -1426,7 +1538,7 @@ abstract class BaseQuery
         return $sql;
     }
 
-    protected function getFieldPathForOrderBy(Entity $entity, string $orderBy, array $params) : ?string
+    protected function getAttributePathForOrderBy(Entity $entity, string $orderBy, array $params) : ?string
     {
         if (strpos($orderBy, '.') !== false || strpos($orderBy, ':') !== false) {
             return $this->convertComplexExpression(
@@ -1437,7 +1549,7 @@ abstract class BaseQuery
             );
         }
 
-        return $this->getFieldPath($entity, $orderBy, $params);
+        return $this->getAttributePath($entity, $orderBy, $params);
     }
 
     protected function getAggregationSelectPart(Entity $entity, string $aggregation, string $aggregationBy, bool $distinct = false) : ?string
@@ -1461,6 +1573,7 @@ abstract class BaseQuery
 
     /**
      * Quote a value.
+     * @todo Make protected.
      */
     public function quote($value) : string
     {
@@ -1474,16 +1587,16 @@ abstract class BaseQuery
     }
 
     /**
-     * Convert a camelCase string to a corresponding representation for DB.
+     * {@inheritdoc)
      */
-    public function toDb(string $attribute) : string
+    public function toDb(string $string) : string
     {
-        if (!array_key_exists($attribute, $this->attributeDbMapCache)) {
-            $attribute[0] = strtolower($attribute[0]);
-            $this->attributeDbMapCache[$attribute] = preg_replace_callback('/([A-Z])/', [$this, 'toDbMatchConversion'], $attribute);
+        if (!array_key_exists($string, $this->attributeDbMapCache)) {
+            $string[0] = strtolower($string[0]);
+            $this->attributeDbMapCache[$string] = preg_replace_callback('/([A-Z])/', [$this, 'toDbMatchConversion'], $string);
         }
 
-        return $this->attributeDbMapCache[$attribute];
+        return $this->attributeDbMapCache[$string];
     }
 
     protected function toDbMatchConversion(array $matches) : string
@@ -1533,13 +1646,15 @@ abstract class BaseQuery
         return $aliases;
     }
 
-    protected function getFieldPath(Entity $entity, $field, &$params = null) : ?string
+    protected function getAttributePath(Entity $entity, string $attribute, ?array &$params = null) : ?string
     {
-        if (!isset($entity->getAttributes()[$field])) {
+        if (!isset($entity->getAttributes()[$attribute])) {
             return null;
         }
 
-        $f = $entity->getAttributes()[$field];
+        $entityType = $entity->getEntityType();
+
+        $f = $entity->getAttributes()[$attribute];
 
         $relationType = $f['type'];
 
@@ -1553,46 +1668,48 @@ abstract class BaseQuery
             return null;
         }
 
-        $fieldPath = '';
-
         switch ($relationType) {
             case 'foreign':
-                if (isset($f['relation'])) {
-                    $relationName = $f['relation'];
+                $relationName = $f['relation'] ?? null;
 
-                    $foreign = $f['foreign'];
-
-                    if (is_array($foreign)) {
-                        $wsCount = 0;
-                        foreach ($foreign as $i => $value) {
-                            if ($value == ' ') {
-                                $foreign[$i] = '\' \'';
-                                $wsCount ++;
-                            } else {
-                                $item =  $this->getAlias($entity, $relationName) . '.' . $this->toDb($value);
-
-                                $foreign[$i] = "IFNULL({$item}, '')";
-                            }
-                        }
-
-                        $fieldPath = 'TRIM(CONCAT(' . implode(', ', $foreign). '))';
-
-                        if ($wsCount > 1) {
-                            $fieldPath = "REPLACE({$fieldPath}, '  ', ' ')";
-                        }
-
-                        $fieldPath = "NULLIF({$fieldPath}, '')";
-                    } else {
-                        $expression = $this->getAlias($entity, $relationName) . '.' . $foreign;
-                        $fieldPath = $this->convertComplexExpression($entity, $expression, false, $params);
-                    }
+                if (!$relationName) {
+                    return null;
                 }
-                break;
-            default:
-                $fieldPath = $this->toDb($entity->getEntityType()) . '.' . $this->toDb($this->sanitize($field));
+
+                $relationName = $f['relation'];
+
+                $foreign = $f['foreign'];
+
+                if (is_array($foreign)) {
+                    $wsCount = 0;
+
+                    foreach ($foreign as $i => $value) {
+                        if ($value == ' ') {
+                            $foreign[$i] = '\' \'';
+                            $wsCount ++;
+                        } else {
+                            $item =  $this->getAlias($entity, $relationName) . '.' . $this->toDb($value);
+
+                            $foreign[$i] = "IFNULL({$item}, '')";
+                        }
+                    }
+
+                    $path = 'TRIM(CONCAT(' . implode(', ', $foreign). '))';
+
+                    if ($wsCount > 1) {
+                        $path = "REPLACE({$path}, '  ', ' ')";
+                    }
+
+                    $path = "NULLIF({$path}, '')";
+                } else {
+                    $expression = $this->getAlias($entity, $relationName) . '.' . $foreign;
+                    $path = $this->convertComplexExpression($entity, $expression, false, $params);
+                }
+
+                return $path;
         }
 
-        return $fieldPath;
+        return $this->toDb($entityType) . '.' . $this->toDb($this->sanitize($attribute));
     }
 
     protected function getWherePart(
@@ -1777,7 +1894,7 @@ abstract class BaseQuery
                                             $params
                                         );
                                     } else {
-                                        $leftPart = $this->getFieldPath($entity, $field, $params);
+                                        $leftPart = $this->getAttributePath($entity, $field, $params);
                                     }
                                 }
                             }
@@ -1864,10 +1981,7 @@ abstract class BaseQuery
         return $joinAlias;
     }
 
-    /**
-     * Convert a value to a string.
-     */
-    public function stringifyValue($value) : string
+    protected function stringifyValue($value) : string
     {
         if (is_array($value)) {
             $arr = [];
@@ -1892,6 +2006,7 @@ abstract class BaseQuery
 
     /**
      * Sanitize an alias for a SELECT statement.
+     * @todo Make protected?
      */
     public function sanitizeSelectAlias(string $string) : string
     {
@@ -2043,8 +2158,9 @@ abstract class BaseQuery
         }
     }
 
-    protected function getJoinItemPart(Entity $entity, $name, $isLeft = false, $conditions = [], $alias = null, array $params = [])
-    {
+    protected function getJoinItemPart(
+        Entity $entity, string $name, bool $isLeft = false, array $conditions = [], ?string $alias = null, array $params = []
+    ) : string {
         $prefix = ($isLeft) ? 'LEFT ' : '';
 
         if (!$entity->hasRelation($name)) {
diff --git a/application/Espo/ORM/DB/Query/Functions.php b/application/Espo/ORM/QueryComposer/Functions.php
similarity index 99%
rename from application/Espo/ORM/DB/Query/Functions.php
rename to application/Espo/ORM/QueryComposer/Functions.php
index 7aeb59f701..c07111852f 100644
--- a/application/Espo/ORM/DB/Query/Functions.php
+++ b/application/Espo/ORM/QueryComposer/Functions.php
@@ -27,7 +27,7 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB\Query;
+namespace Espo\ORM\QueryComposer;
 
 class Functions
 {
diff --git a/application/Espo/ORM/DB/Query/MysqlQuery.php b/application/Espo/ORM/QueryComposer/MysqlQueryComposer.php
similarity index 95%
rename from application/Espo/ORM/DB/Query/MysqlQuery.php
rename to application/Espo/ORM/QueryComposer/MysqlQueryComposer.php
index 3395ce7d3d..6c9fe5a659 100644
--- a/application/Espo/ORM/DB/Query/MysqlQuery.php
+++ b/application/Espo/ORM/QueryComposer/MysqlQueryComposer.php
@@ -27,9 +27,9 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\DB\Query;
+namespace Espo\ORM\QueryComposer;
 
-class MysqlQuery extends BaseQuery
+class MysqlQueryComposer extends BaseQueryComposer
 {
     public function limit(string $sql, ?int $offset = null, ?int $limit = null) : string
     {
diff --git a/application/Espo/ORM/QueryComposer/QueryComposer.php b/application/Espo/ORM/QueryComposer/QueryComposer.php
new file mode 100644
index 0000000000..13d439aad8
--- /dev/null
+++ b/application/Espo/ORM/QueryComposer/QueryComposer.php
@@ -0,0 +1,57 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryComposer;
+
+use Espo\ORM\{
+    QueryParams\Query as Query,
+};
+
+interface QueryComposer
+{
+    /**
+     * Compose a SQL query by a given query parameters.
+     */
+    public function compose(Query $query) : string;
+
+    /**
+     * Convert a camelCase string to a corresponding representation for DB.
+     */
+    public function toDb(string $string) : string;
+
+    /**
+     * Sanitize a string.
+     */
+    public function sanitize(string $string) : string;
+
+    /**
+     * Sanitize an alias for a SELECT statement.
+     */
+    public function sanitizeSelectAlias(string $string);
+}
diff --git a/application/Espo/ORM/QueryExecutor.php b/application/Espo/ORM/QueryExecutor.php
new file mode 100644
index 0000000000..1aa75cba69
--- /dev/null
+++ b/application/Espo/ORM/QueryExecutor.php
@@ -0,0 +1,56 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM;
+
+use Espo\ORM\{
+    QueryParams\Query,
+};
+
+use PDOStatement;
+
+/**
+ * Runs queries by given query params instances.
+ */
+class QueryExecutor
+{
+    protected $entityManager;
+
+    public function __construct(EntityManager $entityManager)
+    {
+        $this->entityManager = $entityManager;
+    }
+
+    public function run(Query $query) : PDOStatement
+    {
+        $sql = $this->entityManager->getQueryComposer()->compose($query);
+
+        return $this->entityManager->runSql($sql, true);
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/BaseBuilderTrait.php b/application/Espo/ORM/QueryParams/BaseBuilderTrait.php
new file mode 100644
index 0000000000..71f1a70082
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/BaseBuilderTrait.php
@@ -0,0 +1,56 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+use RuntimeException;
+
+trait BaseBuilderTrait
+{
+    protected $params = [];
+
+    public function __construct()
+    {
+    }
+
+    protected function isEmpty() : bool
+    {
+        return empty($this->params);
+    }
+
+    protected function cloneInternal(Query $query)
+    {
+        if (!$this->isEmpty()) {
+            throw new RuntimeException("Clone can be called only on a new empty builder instance.");
+        }
+
+        $this->params = $query->getRawParams();
+    }
+
+}
diff --git a/application/Espo/ORM/RDBSelect.php b/application/Espo/ORM/QueryParams/BaseTrait.php
similarity index 76%
rename from application/Espo/ORM/RDBSelect.php
rename to application/Espo/ORM/QueryParams/BaseTrait.php
index 17a99592c3..2d50d173c7 100644
--- a/application/Espo/ORM/RDBSelect.php
+++ b/application/Espo/ORM/QueryParams/BaseTrait.php
@@ -27,40 +27,35 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM;
+namespace Espo\ORM\QueryParams;
 
-/**
- * Select parameters.
- */
-class RDBSelect
+trait BaseTrait
 {
-    protected $entityType;
-
-    protected $params;
-
-    public function __construct(string $entityType, array $params)
-    {
-        $this->entityType = $entityType;
-        $this->params = $params;
-    }
-
-    /**
-     * Get an entity type.
-     */
-    public function getEntityType() : string
-    {
-        return $this->entityType;
-    }
+    protected $params = [];
 
     /**
      * Get parameters in RAW format.
      */
     public function getRawParams() : array
     {
-        $params = $this->params;
+        return $this->params;
+    }
 
-        $params['from'] = $this->entityType
+    /**
+     * Create from RAW params.
+     */
+    public static function fromRaw(array $params) : self
+    {
+        $obj = new self();
 
-        return $params;
+        $obj->validateRawParams($params);
+
+        $obj->params = $params;
+
+        return $obj;
+    }
+
+    protected function validateRawParams(array $params)
+    {
     }
 }
diff --git a/application/Espo/ORM/QueryParams/Builder.php b/application/Espo/ORM/QueryParams/Builder.php
new file mode 100644
index 0000000000..373228376f
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/Builder.php
@@ -0,0 +1,49 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+/**
+ * Builds query parameters.
+ * Builder instances are one-off, meaning that you need to instantiate it for every new building process.
+ */
+interface Builder
+{
+    /**
+     * Build a query instance.
+     * @todo Uncomment when 7.4 is a min supported PHP version. Need the support of contravariant method parameters.
+     */
+    //public function build() : Query;
+
+    /**
+     * Clone an existing query for a further modification and building.
+     * @todo Uncomment when 7.4 is a min supported PHP version. Need the support of contravariant method parameters.
+     */
+    //public function clone(Query $query) : self;
+}
diff --git a/application/Espo/ORM/QueryParams/Delete.php b/application/Espo/ORM/QueryParams/Delete.php
new file mode 100644
index 0000000000..cdb3bc473e
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/Delete.php
@@ -0,0 +1,46 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+use RuntimeException;
+
+/**
+ * Delete parameters.
+ */
+class Delete implements Query
+{
+    use SelectingTrait;
+    use BaseTrait;
+
+    protected function validateRawParams(array $params)
+    {
+        $this->validateRawParamsSelecting($params);
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/DeleteBuilder.php b/application/Espo/ORM/QueryParams/DeleteBuilder.php
new file mode 100644
index 0000000000..b7d5713a42
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/DeleteBuilder.php
@@ -0,0 +1,63 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+class DeleteBuilder implements Builder
+{
+    use SelectingBuilderTrait;
+
+    /**
+     * Build a DELETE query.
+     */
+    public function build() : Delete
+    {
+        return Delete::fromRaw($this->params);
+    }
+
+    /**
+     * Clone an existing query for a subsequent modifying and building.
+     */
+    public function clone(Delete $query) : self
+    {
+        $this->cloneInternal($query);
+
+        return $this;
+    }
+
+    /**
+     * Apply LIMIT.
+     */
+    public function limit(?int $limit = null) : self
+    {
+        $this->params['limit'] = $limit;
+
+        return $this;
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/Insert.php b/application/Espo/ORM/QueryParams/Insert.php
new file mode 100644
index 0000000000..d42122ec49
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/Insert.php
@@ -0,0 +1,69 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+use RuntimeException;
+
+/**
+ * Insert parameters.
+ */
+class Insert implements Query
+{
+    use BaseTrait;
+
+    protected function validateRawParams(array $params)
+    {
+        $into = $params['into'] ?? null;
+
+        if (!$into || !is_string($into)) {
+            throw new RuntimeException("Bad or missing 'into' parameter.");
+        }
+
+        $columns = $params['columns'] = $params['columns'] ?? [];
+
+        if (!is_array($columns)) {
+            throw new RuntimeException("Bad 'columns' parameter.");
+        }
+
+        $values = $params['values'] = $params['values'] ?? [];
+
+        $valuesSelectParams = $params['valuesSelectParams'] = $params['valuesSelectParams'] ?? null;
+
+        if (!is_array($values)) {
+            throw new RuntimeException("Bad 'values' parameter.");
+        }
+
+        $updateSet = $params['updateSet'] = $params['updateSet'] ?? null;
+
+        if ($updateSet && !is_array($updateSet)) {
+            throw new RuntimeException("Bad 'updateSet' parameter.");
+        }
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/InsertBuilder.php b/application/Espo/ORM/QueryParams/InsertBuilder.php
new file mode 100644
index 0000000000..99dbcc0402
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/InsertBuilder.php
@@ -0,0 +1,103 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+class InsertBuilder implements Builder
+{
+    use BaseBuilderTrait;
+
+    protected $params = [];
+
+    /**
+     * Build a INSERT query.
+     */
+    public function build() : Insert
+    {
+        return Insert::fromRaw($this->params);
+    }
+
+    /**
+     * Clone an existing query for a subsequent modifying and building.
+     */
+    public function clone(Insert $query) : self
+    {
+        $this->cloneInternal($query);
+    }
+
+    /**
+     * Into what entity type to insert.
+     */
+    public function into(string $entityType) : self
+    {
+        $this->params['into'] = $entityType;
+
+        return $this;
+    }
+
+    /**
+     * What columns to set with values. A list of columns.
+     */
+    public function columns(array $columns) : self
+    {
+        $this->params['columns'] = $columns;
+
+        return $this;
+    }
+
+    /**
+     * What values to insert. A key-value map or a list of key-value maps.
+     */
+    public function values(array $values) : self
+    {
+        $this->params['values'] = $values;
+
+        return $this;
+    }
+
+    /**
+     * Values to set on duplicate key. A key-value map.
+     */
+    public function updateSet(array $updateSet) : self
+    {
+        $this->params['updateSet'] = $updateSet;
+
+        return $this;
+    }
+
+    /**
+     * For a mass insert by a select sub-query.
+     */
+    public function valuesQuery(Select $query) : self
+    {
+        $this->params['valuesSelectParams'] = $query->getRawParams();
+
+        return $this;
+    }
+}
diff --git a/application/Espo/ORM/Repositories/Removable.php b/application/Espo/ORM/QueryParams/Query.php
similarity index 84%
rename from application/Espo/ORM/Repositories/Removable.php
rename to application/Espo/ORM/QueryParams/Query.php
index bfd5af40bc..5ec30050b0 100644
--- a/application/Espo/ORM/Repositories/Removable.php
+++ b/application/Espo/ORM/QueryParams/Query.php
@@ -27,14 +27,15 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\Repositories;
+namespace Espo\ORM\QueryParams;
 
-use Espo\ORM\Entity;
-
-interface Removable
+/**
+ * Query parameters. Instances are immutable. Need to clone with a builder to get a copy for a further modification.
+ */
+interface Query
 {
     /**
-     * Remove a record (mark as deleted).
+     * Get parameters in RAW format.
      */
-    public function remove(Entity $entity);
+    public function getRawParams() : array;
 }
diff --git a/application/Espo/ORM/QueryParams/Select.php b/application/Espo/ORM/QueryParams/Select.php
new file mode 100644
index 0000000000..f542471b51
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/Select.php
@@ -0,0 +1,65 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+/**
+ * Select parameters.
+ *
+ * @todo Add validation and normalization (from ORM\DB\BaseQuery).
+ */
+class Select implements Query
+{
+    use SelectingTrait;
+    use BaseTrait;
+
+    const ORDER_ASC = 'ASC';
+    const ORDER_DESC = 'DESC';
+
+    /**
+     * @todo Remove?
+     */
+    public function isSth() : bool
+    {
+        return $this->params['sth'] ?? false;
+    }
+
+    /**
+     * Get select items.
+     */
+    public function getSelect() : array
+    {
+        return $this->params['select'] ?? [];
+    }
+
+    protected function validateRawParams(array $params)
+    {
+        $this->validateRawParamsSelecting($params);
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/SelectBuilder.php b/application/Espo/ORM/QueryParams/SelectBuilder.php
new file mode 100644
index 0000000000..94885f2503
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/SelectBuilder.php
@@ -0,0 +1,150 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+use InvalidArgumentException;
+
+class SelectBuilder implements Builder
+{
+    use SelectingBuilderTrait;
+
+    /**
+     * Build a SELECT query.
+     */
+    public function build() : Select
+    {
+        return Select::fromRaw($this->params);
+    }
+
+    /**
+     * Clone an existing query for a subsequent modifying and building.
+     */
+    public function clone(Select $query) : self
+    {
+        $this->cloneInternal($query);
+
+        return $this;
+    }
+
+    /**
+     * Set to return STH collection. Recommended for fetching large number of records.
+     *
+     * @todo Remove.
+     */
+    public function sth() : self
+    {
+        $this->params['returnSthCollection'] = true;
+
+        return $this;
+    }
+
+    /**
+     * Apply OFFSET and LIMIT.
+     */
+    public function limit(?int $offset = null, ?int $limit = null) : self
+    {
+        $this->params['offset'] = $offset;
+        $this->params['limit'] = $limit;
+
+        return $this;
+    }
+
+    /**
+     * Specify SELECT. Columns and expressions to be selected. If not called, then all entity attributes will be selected.
+     * Passing an array will reset previously set items.
+     * Passing a string will append an item.
+     *
+     * Usage options:
+     * * `select([$item1, $item2, ...])`
+     * * `select(string $expression)`
+     * * `select(string $expression, string $alias)`
+     *
+     * @param array|string $select
+     */
+    public function select($select, ?string $alias = null) : self
+    {
+        if (is_array($select)) {
+            $this->params['select'] = $select;
+
+            return $this;
+        }
+
+        if (is_string($select)) {
+            $this->params['select'] = $this->params['select'] ?? [];
+
+            if ($alias) {
+                $this->params['select'][] = [$select, $alias];
+            } else {
+                $this->params['select'][] = $select;
+            }
+
+            return $this;
+        }
+
+        throw new InvalidArgumentException();
+    }
+
+    /**
+     * Specify GROUP BY.
+     */
+    public function groupBy(array $groupBy) : self
+    {
+        $this->params['groupBy'] = $groupBy;
+
+        return $this;
+    }
+
+    /**
+     * Add a HAVING clause.
+     *
+     * Two usage options:
+     * * `having(array $havingClause)`
+     * * `having(string $key, string $value)`
+     *
+     * @param array|string $keyOrClause
+     * @param ?array|string $value
+     */
+    public function having($keyOrClause = [], $value = null) : self
+    {
+        $this->applyWhereClause('havingClause', $keyOrClause, $value);
+
+        return $this;
+    }
+
+    /**
+     * @todo Remove?
+     */
+    public function withDeleted() : self
+    {
+        $this->params['withDeleted'] = true;
+
+        return $this;
+    }
+}
diff --git a/application/Espo/ORM/QueryParams/SelectingBuilderTrait.php b/application/Espo/ORM/QueryParams/SelectingBuilderTrait.php
new file mode 100644
index 0000000000..5be924050b
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/SelectingBuilderTrait.php
@@ -0,0 +1,208 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+trait SelectingBuilderTrait
+{
+    use BaseBuilderTrait;
+
+    /**
+     * Set FROM parameter. For what entity type to build a query.
+     */
+    public function from(string $entityType) : self
+    {
+        if (isset($this->params['from'])) {
+            throw new LogicException("Method 'from' can be called only once.");
+        }
+
+        $this->params['from'] = $entityType;
+
+        return $this;
+    }
+
+    /**
+     * Set DISTINCT parameter.
+     */
+    public function distinct() : self
+    {
+        $this->params['distinct'] = true;
+
+        return $this;
+    }
+
+    /**
+     * Add a WHERE clause.
+     *
+     * Two usage options:
+     * * `where(array $whereClause)`
+     * * `where(string $key, string $value)`
+     *
+     * @param array|string $keyOrClause A key or where clause.
+     * @param ?array|string $value A value. If the first argument is an array, then should be omited.
+     */
+    public function where($keyOrClause = [], $value = null) : self
+    {
+        $this->applyWhereClause('whereClause', $keyOrClause, $value);
+
+        return $this;
+    }
+
+    protected function applyWhereClause(string $type, $keyOrClause, $value)
+    {
+        $this->params[$type] = $this->params[$type] ?? [];
+
+        $original = $this->params[$type];
+
+        if (!is_string($keyOrClause) && !is_array($keyOrClause)) {
+            throw new InvalidArgumentException();
+        }
+
+        if (is_array($keyOrClause)) {
+            $new = $keyOrClause;
+        }
+
+        if (is_string($keyOrClause)) {
+            $new = [$keyOrClause => $value];
+        }
+
+        $containsSameKeys = (bool) count(
+            array_intersect(
+                array_keys($new),
+                array_keys($original)
+            )
+        );
+
+        if ($containsSameKeys) {
+            $this->params[$type][] = $new;
+
+            return $this;
+        }
+
+        $this->params[$type] = $new + $original;
+
+        return $this;
+    }
+
+    /**
+     * Apply ORDER.
+     *
+     * @param string|array $orderBy An attribute to order by or order definitions as an array.
+     * @param bool|string $direction 'ASC' or 'DESC'. TRUE for DESC order.
+     *                               If the first argument is an array then should be omitied.
+     */
+    public function order($orderBy, $direction = Select::ORDER_ASC) : self
+    {
+        if (!$orderBy) {
+            throw InvalidArgumentException();
+        }
+
+        $this->params['orderBy'] = $orderBy;
+        $this->params['order'] = $direction;
+
+        return $this;
+    }
+
+    /**
+     * Add JOIN.
+     *
+     * @param string $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
+     *
+     */
+    public function join($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        if (empty($this->params['joins'])) {
+            $this->params['joins'] = [];
+        }
+
+        if (is_array($relationName)) {
+            $joinList = $relationName;
+
+            foreach ($joinList as $item) {
+                $this->params['joins'][] = $item;
+            }
+
+            return $this;
+        }
+
+        if (is_null($alias) && is_null($conditions)) {
+            $this->params['joins'][] = $relationName;
+
+            return $this;
+        }
+
+        if (is_null($conditions)) {
+            $this->params['joins'][] = [$relationName, $alias];
+
+            return $this;
+        }
+
+        $this->params['joins'][] = [$relationName, $alias, $conditions];
+
+        return $this;
+    }
+
+    /**
+     * Add LEFT JOIN.
+     *
+     * @param string $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
+     */
+    public function leftJoin($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        if (empty($this->params['leftJoins'])) {
+            $this->params['leftJoins'] = [];
+        }
+
+        if (is_array($relationName)) {
+            $joinList = $relationName;
+
+            foreach ($joinList as $item) {
+                $this->params['leftJoins'][] = $item;
+            }
+
+            return $this;
+        }
+
+        if (is_null($alias) && is_null($conditions)) {
+            $this->params['leftJoins'][] = $relationName;
+
+            return $this;
+        }
+
+        if (is_null($conditions)) {
+            $this->params['leftJoins'][] = [$relationName, $alias];
+
+            return $this;
+        }
+
+        $this->params['leftJoins'][] = [$relationName, $alias, $conditions];
+
+        return $this;
+    }
+}
diff --git a/application/Espo/ORM/Repositories/Findable.php b/application/Espo/ORM/QueryParams/SelectingTrait.php
similarity index 75%
rename from application/Espo/ORM/Repositories/Findable.php
rename to application/Espo/ORM/QueryParams/SelectingTrait.php
index 98a9b839b8..c0fc52783c 100644
--- a/application/Espo/ORM/Repositories/Findable.php
+++ b/application/Espo/ORM/QueryParams/SelectingTrait.php
@@ -27,27 +27,26 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\Repositories;
+namespace Espo\ORM\QueryParams;
 
-use Espo\ORM\{
-    Entity,
-    Collection,
-};
+use RuntimeException;
 
-interface Findable
+trait SelectingTrait
 {
     /**
-     * A number of records matching specific parameters.
+     * Get an entity type.
      */
-    public function count(array $params) : int;
+    public function getFrom() : string
+    {
+        return $this->params['from'];
+    }
 
-    /**
-     * Find records matching specific parameters.
-     */
-    public function find(array $params) : Collection;
+    protected static function validateRawParamsSelecting(array $params)
+    {
+        $from = $params['from'] ?? null;
 
-    /**
-     * Find the first record matching specific parameters.
-     */
-    public function findOne(array $params) : ?Entity;
+        if (!$from || !is_string($from)) {
+            throw new RuntimeException("Select params: Missing 'from'.");
+        }
+    }
 }
diff --git a/application/Espo/ORM/QueryParams/Update.php b/application/Espo/ORM/QueryParams/Update.php
new file mode 100644
index 0000000000..330cbd8a6f
--- /dev/null
+++ b/application/Espo/ORM/QueryParams/Update.php
@@ -0,0 +1,52 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\QueryParams;
+
+use RuntimeException;
+
+/**
+ * Update parameters.
+ */
+class Update implements Query
+{
+    use SelectingTrait;
+    use BaseTrait;
+
+    protected function validateRawParams(array $params)
+    {
+        $this->validateRawParamsSelecting($params);
+
+        $set = $params['set'] ?? null;
+
+        if (!$set || !is_array($set)) {
+            throw new RuntimeException("Update params: Bad or missing 'set' parameter.");
+        }
+    }
+}
diff --git a/application/Espo/ORM/Sth2Collection.php b/application/Espo/ORM/QueryParams/UpdateBuilder.php
similarity index 66%
rename from application/Espo/ORM/Sth2Collection.php
rename to application/Espo/ORM/QueryParams/UpdateBuilder.php
index 81dcee7c22..554b4b203c 100644
--- a/application/Espo/ORM/Sth2Collection.php
+++ b/application/Espo/ORM/QueryParams/UpdateBuilder.php
@@ -27,37 +27,46 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM;
+namespace Espo\ORM\QueryParams;
 
-use Espo\ORM\DB\Query\BaseQuery as Query;
+use LogicException;
 
-use PDO;
-
-class Sth2Collection extends SthCollection
+class UpdateBuilder implements Builder
 {
-    public function __construct(
-        string $entityType, EntityFactory $entityFactory, Query $query, PDO $pdo, array $selectParams = []
-    ) {
-        $this->selectParams = $selectParams;
-        $this->entityType = $entityType;
+    use SelectingBuilderTrait;
 
-        $this->entityFactory = $entityFactory;
-        $this->query = $query;
-        $this->pdo = $pdo;
+    /**
+     * Build a UPDATE query.
+     */
+    public function build() : Update
+    {
+        return Update::fromRaw($this->params);
     }
 
-    protected function getQuery()
+    /**
+     * Clone an existing query for a subsequent modifying and building.
+     */
+    public function clone(Delete $query) : self
     {
-        return $this->query;
+        $this->cloneInternal($query);
+
+        return $this;
     }
 
-    protected function getPdo()
+    public function set(array $set) : self
     {
-        return $this->pdo;
+        $this->params['set'] = $set;
+
+        return $this;
     }
 
-    protected function getEntityFactory()
+    /**
+     * Apply LIMIT.
+     */
+    public function limit(?int $limit = null) : self
     {
-        return $this->entityFactory;
+        $this->params['limit'] = $limit;
+
+        return $this;
     }
 }
diff --git a/application/Espo/ORM/RDBSelectBuilder.php b/application/Espo/ORM/RDBSelectBuilder.php
deleted file mode 100644
index f9664474e4..0000000000
--- a/application/Espo/ORM/RDBSelectBuilder.php
+++ /dev/null
@@ -1,374 +0,0 @@
-<?php
-/************************************************************************
- * This file is part of EspoCRM.
- *
- * EspoCRM - Open Source CRM application.
- * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
- * Website: https://www.espocrm.com
- *
- * EspoCRM is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * EspoCRM is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
- *
- * The interactive user interfaces in modified source and object code versions
- * of this program must display Appropriate Legal Notices, as required under
- * Section 5 of the GNU General Public License version 3.
- *
- * In accordance with Section 7(b) of the GNU General Public License version 3,
- * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
- ************************************************************************/
-
-namespace Espo\ORM;
-
-use Espo\Core\Exceptions\Error;
-
-use Espo\ORM\{
-    Repositories\Findable,
-    Collection,
-    Entity,
-};
-
-/**
- * Builds select parameters for an RDB repository and invokes findable methods.
- */
-class RDBSelectBuilder implements Findable
-{
-    protected $whereClause = [];
-
-    protected $havingClause = [];
-
-    protected $params = [];
-
-    protected $entityManager;
-
-    protected $repository;
-
-    protected $entityType = null;
-
-    public function __construct(EntityManager $entityManager)
-    {
-        $this->entityManager = $entityManager;
-    }
-
-    public function from(string $entityType) : self
-    {
-        if ($this->repository) {
-            throw new Error("SelectBuilder: Method 'from' can be called only once.");
-        }
-
-        $this->entityType = $entityType;
-        $this->repository = $this->entityManager->getRepository($entityType);
-
-        return $this;
-    }
-
-    protected function isExecutable() : bool
-    {
-        return (bool) $this->entityType;
-    }
-
-    protected function processExecutableCheck()
-    {
-        if (!$this->isExecutable()) {
-            throw new Error("SelectBuilder: Method 'from' must be called.");
-        }
-    }
-
-    public function find(array $params = []) : Collection
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams($params);
-        return $this->repository->find($params);
-    }
-
-    public function findOne(array $params = []) : ?Entity
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams($params);
-        return $this->repository->findOne($params);
-    }
-
-    public function count(array $params = []) : int
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams($params);
-        return $this->repository->count($params);
-    }
-
-    public function max(string $attribute)
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams();
-        return $this->repository->max($attribute, $params);
-    }
-
-    public function min(string $attribute)
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams();
-        return $this->repository->min($attribute, $params);
-    }
-
-    public function sum(string $attribute)
-    {
-        $this->processExecutableCheck();
-
-        $params = $this->getMergedParams();
-        return $this->repository->sum($attribute, $params);
-    }
-
-    /**
-     * Add JOIN.
-     *
-     * @param string|array $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
-     *
-     * Usage options:
-     * * `join(string $relationName)`
-     * * `join(array $joinDefinitionList)`
-     *
-     * Usage examples:
-     * ```
-     * ->join($relationName)
-     * ->join($relationName, $alias, $conditions)
-     * ->join([$relationName1, $relationName2, ...])
-     * ->join([[$relationName, $alias], ...])
-     * ->join([[$relationName, $alias, $conditions], ...])
-     * ```
-     */
-    public function join($relationName, ?string $alias = null, ?array $conditions = null) : self
-    {
-        if (empty($this->params['joins'])) {
-            $this->params['joins'] = [];
-        }
-
-        if (is_array($relationName)) {
-            $joinList = $relationName;
-            foreach ($joinList as $item) {
-                $this->params['joins'][] = $item;
-            }
-            return $this;
-        }
-
-        if (is_null($alias) && is_null($conditions)) {
-            $this->params['joins'][] = $relationName;
-            return $this;
-        }
-
-        if (is_null($conditions)) {
-            $this->params['joins'][] = [$relationName, $alias];
-            return $this;
-        }
-
-        $this->params['joins'][] = [$relationName, $alias, $conditions];
-        return $this;
-    }
-
-    /**
-     * Add LEFT JOIN.
-     *
-     * @param string|array $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
-     *
-     * This method works the same way as `join` method.
-     */
-    public function leftJoin($relationName, ?string $alias = null, ?array $conditions = null) : self
-    {
-        if (empty($this->params['leftJoins'])) {
-            $this->params['leftJoins'] = [];
-        }
-
-        if (is_array($relationName)) {
-            $joinList = $relationName;
-            foreach ($joinList as $item) {
-                $this->params['leftJoins'][] = $item;
-            }
-            return $this;
-        }
-
-        if (is_null($alias) && is_null($conditions)) {
-            $this->params['leftJoins'][] = $relationName;
-            return $this;
-        }
-
-        if (is_null($conditions)) {
-            $this->params['leftJoins'][] = [$relationName, $alias];
-            return $this;
-        }
-
-        $this->params['leftJoins'][] = [$relationName, $alias, $conditions];
-        return $this;
-    }
-
-    /**
-     * Set DISTINCT parameter.
-     */
-    public function distinct() : self
-    {
-        $this->params['distinct'] = true;
-
-        return $this;
-    }
-
-    /**
-     * Set to return STH collection. Recommended fetching large number of records.
-     */
-    public function sth() : self
-    {
-        $this->params['returnSthCollection'] = true;
-
-        return $this;
-    }
-
-    /**
-     * Add a WHERE clause.
-     *
-     * Two usage options:
-     * * `where(array $whereClause)`
-     * * `where(string $key, string $value)`
-     */
-    public function where($param1 = [], $param2 = null) : self
-    {
-        if (is_array($param1)) {
-            $this->whereClause = $param1 + $this->whereClause;
-
-        } else {
-            if (!is_null($param2)) {
-                $this->whereClause[] = [$param1 => $param2];
-            }
-        }
-
-        return $this;
-    }
-
-    /**
-     * Add a HAVING clause.
-     *
-     * Two usage options:
-     * * `having(array $havingClause)`
-     * * `having(string $key, string $value)`
-     */
-    public function having($param1 = [], $param2 = null) : self
-    {
-        if (is_array($param1)) {
-            $this->havingClause = $param1 + $this->havingClause;
-        } else {
-            if (!is_null($param2)) {
-                $this->havingClause[] = [$param1 => $param2];
-            }
-        }
-
-        return $this;
-    }
-
-    /**
-     * Apply ORDER.
-     *
-     * @param string|array $attribute An attribute to order by or order definitions as an array.
-     * @param bool|string $direction TRUE for DESC order.
-     */
-    public function order($attribute = 'id', $direction = 'ASC') : self
-    {
-        $this->params['orderBy'] = $attribute;
-        $this->params['order'] = $direction;
-
-        return $this;
-    }
-
-    /**
-     * Apply OFFSET and LIMIT.
-     */
-    public function limit(?int $offset = null, ?int $limit = null) : self
-    {
-        $this->params['offset'] = $offset;
-        $this->params['limit'] = $limit;
-
-        return $this;
-    }
-
-    /**
-     * Specify SELECT. Which attributes to select. All attributes are selected by default.
-     */
-    public function select(array $select) : self
-    {
-        $this->params['select'] = $select;
-
-        return $this;
-    }
-
-    /**
-     * Specify GROUP BY.
-     */
-    public function groupBy(array $groupBy) : self
-    {
-        $this->params['groupBy'] = $groupBy;
-
-        return $this;
-    }
-
-    /**
-     * Builds result select parameters.
-     */
-    public function build() : RDBSelect
-    {
-        $this->processExecutableCheck();
-
-        return new RDBSelect($this->entityType, $this->getMergedParams());
-    }
-
-    protected function getMergedParams(array $params = []) : array
-    {
-        if (isset($params['whereClause'])) {
-            $params['whereClause'] = $params['whereClause'];
-            if (!empty($this->whereClause)) {
-                $params['whereClause'][] = $this->whereClause;
-            }
-        } else {
-            $params['whereClause'] = $this->whereClause;
-        }
-        if (!empty($params['havingClause'])) {
-            $params['havingClause'] = $params['havingClause'];
-            if (!empty($this->havingClause)) {
-                $params['havingClause'][] = $this->havingClause;
-            }
-        } else {
-            $params['havingClause'] = $this->havingClause;
-        }
-
-        if (empty($params['whereClause'])) {
-            unset($params['whereClause']);
-        }
-
-        if (empty($params['havingClause'])) {
-            unset($params['havingClause']);
-        }
-
-        if (!empty($params['leftJoins']) && !empty($this->params['leftJoins'])) {
-            foreach ($this->params['leftJoins'] as $j) {
-                $params['leftJoins'][] = $j;
-            }
-        }
-
-        if (!empty($params['joins']) && !empty($this->params['joins'])) {
-            foreach ($this->params['joins'] as $j) {
-                $params['joins'][] = $j;
-            }
-        }
-
-        $params = array_replace_recursive($this->params, $params);
-
-        return $params;
-    }
-}
diff --git a/application/Espo/ORM/Repository/EmptyHookMediator.php b/application/Espo/ORM/Repository/EmptyHookMediator.php
new file mode 100644
index 0000000000..e48732ffad
--- /dev/null
+++ b/application/Espo/ORM/Repository/EmptyHookMediator.php
@@ -0,0 +1,68 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\Repository;
+
+use Espo\ORM\{
+    Entity,
+    QueryParams\Select,
+};
+
+class EmptyHookMediator implements HookMediator
+{
+    public function beforeSave(Entity $entity, array $options)
+    {}
+
+    public function afterSave(Entity $entity, array $options)
+    {}
+
+    public function beforeRemove(Entity $entity, array $options)
+    {}
+
+    public function afterRemove(Entity $entity, array $options)
+    {}
+
+    public function beforeRelate(Entity $entity, string $relationName, Entity $foreignEntity, ?array $columnData, array $options)
+    {}
+
+    public function afterRelate(Entity $entity, string $relationName, Entity $foreignEntity, ?array $columnData, array $options)
+    {}
+
+    public function beforeUnrelate(Entity $entity, string $relationName, Entity $foreignEntity, array $options)
+    {}
+
+    public function afterUnrelate(Entity $entity, string $relationName, Entity $foreignEntity, array $options)
+    {}
+
+    public function beforeMassRelate(Entity $entity, string $relationName, Select $query, array $options)
+    {}
+
+    public function afterMassRelate(Entity $entity, string $relationName, Select $query, array $options)
+    {}
+}
diff --git a/application/Espo/ORM/Repositories/Relatable.php b/application/Espo/ORM/Repository/HookMediator.php
similarity index 56%
rename from application/Espo/ORM/Repositories/Relatable.php
rename to application/Espo/ORM/Repository/HookMediator.php
index 4f9c8dddab..644dc2023f 100644
--- a/application/Espo/ORM/Repositories/Relatable.php
+++ b/application/Espo/ORM/Repository/HookMediator.php
@@ -27,34 +27,32 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\Repositories;
+namespace Espo\ORM\Repository;
 
-use Espo\ORM\Entity;
+use Espo\ORM\{
+    Entity,
+    QueryParams\Select,
+};
 
-interface Relatable
+interface HookMediator
 {
-    /**
-     * Find records records matching specific parameters.
-     */
-    public function findRelated(Entity $entity, string $relationName, array $params);
+    public function beforeSave(Entity $entity, array $options);
 
-    /**
-     * A number of related records matching specific parameters.
-     */
-    public function countRelated(Entity $entity, string $relationName, array $params = []) : int;
+    public function afterSave(Entity $entity, array $options);
 
-    /**
-     * Whether records are related.
-     */
-    public function isRelated(Entity $entity, string $relationName, $foreign) : bool;
+    public function beforeRemove(Entity $entity, array $options);
 
-    /**
-     * Relate records.
-     */
-    public function relate(Entity $entity, string $relationName, $foreign);
+    public function afterRemove(Entity $entity, array $options);
 
-    /**
-     * Unrelate records.
-     */
-    public function unrelate(Entity $entity, string $relationName, $foreign);
+    public function beforeRelate(Entity $entity, string $relationName, Entity $foreignEntity, ?array $columnData, array $options);
+
+    public function afterRelate(Entity $entity, string $relationName, Entity $foreignEntity, ?array $columnData, array $options);
+
+    public function beforeUnrelate(Entity $entity, string $relationName, Entity $foreignEntity, array $options);
+
+    public function afterUnrelate(Entity $entity, string $relationName, Entity $foreignEntity, array $options);
+
+    public function beforeMassRelate(Entity $entity, string $relationName, Select $query, array $options);
+
+    public function afterMassRelate(Entity $entity, string $relationName, Select $query, array $options);
 }
diff --git a/application/Espo/ORM/Repository/RDBRelation.php b/application/Espo/ORM/Repository/RDBRelation.php
new file mode 100644
index 0000000000..ed984a7686
--- /dev/null
+++ b/application/Espo/ORM/Repository/RDBRelation.php
@@ -0,0 +1,458 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\Repository;
+
+use Espo\ORM\{
+    Collection,
+    Entity,
+    EntityManager,
+    QueryParams\Select,
+    QueryParams\SelectBuilder,
+    Mapper\Mapper,
+};
+
+use RuntimeException;
+use BadMethodCallException;
+
+use StdClass;
+
+/**
+ * An access point for a specific relation of a record.
+ */
+class RDBRelation
+{
+    protected $entityManager;
+
+    protected $hookMediator;
+
+    protected $entity;
+
+    protected $entityType;
+
+    protected $foreignEntityType = null;
+
+    protected $relationName;
+
+    protected $relationType = null;
+
+    protected $builder = null;
+
+    protected $noBuilder = false;
+
+    public function __construct(EntityManager $entityManager, Entity $entity, string $relationName, HookMediator $hookMediator)
+    {
+        $this->entityManager = $entityManager;
+        $this->entity = $entity;
+        $this->hookMediator = $hookMediator;
+
+        if (!$entity->get('id')) {
+            throw new RuntimeException("Can't use an entity w/o ID.");
+        }
+
+        if (!$entity->hasRelation($relationName)) {
+            throw new RuntimeException("Entity does not have a relation '{$relationName}'.");
+        }
+
+        $this->relationName = $relationName;
+
+        $this->relationType = $entity->getRelationType($relationName);
+
+        $this->foreignEntityType = $entity->getRelationParam($relationName, 'entity');
+
+        $this->entityType = $entity->getEntityType();
+
+        if ($this->isBelongsToParentType()) {
+            $this->noBuilder = true;
+        }
+    }
+
+    protected function createBuilder(?Select $query = null) : RDBRelationSelectBuilder
+    {
+        if ($this->noBuilder) {
+            throw new RuntimeException("Can't use query builder for the '{$this->relationType}' relation type.");
+        }
+
+        return new RDBRelationSelectBuilder($this->entityManager, $this->entity, $this->relationName, $query);
+    }
+
+    /**
+     * Clone a query.
+     */
+    public function clone(Select $query) : RDBRelationSelectBuilder
+    {
+        if ($this->noBuilder) {
+            throw new RuntimeException("Can't use clone for the '{$this->relationType}' relation type.");
+        }
+
+        if ($query->getFrom() !== $this->foreignEntityType) {
+            throw new RuntimeException("Passed query doesn't match the entity type.");
+        }
+
+        return $this->createBuilder($query);
+    }
+
+    protected function isBelongsToParentType() : bool
+    {
+        return $this->relationType === Entity::BELONGS_TO_PARENT;
+    }
+
+    protected function getMapper() : Mapper
+    {
+        return $this->entityManager->getMapper();
+    }
+
+    /**
+     * Find related records.
+     */
+    public function find() : Collection
+    {
+        if ($this->isBelongsToParentType()) {
+            $collection = $this->entityManager->getCollectionFactory()->create();
+
+            $entity = $this->getMapper()->selectRelated($this->entity, $this->relationName);
+
+            if ($entity) {
+                $collection[] = $entity;
+            }
+
+            $collection->setAsFetched();
+
+            return $collection;
+        }
+
+        return $this->createBuilder()->find();
+    }
+
+    /**
+     * Find a first record.
+     */
+    public function findOne() : ?Entity
+    {
+        if ($this->isBelongsToParentType()) {
+            return $this->getMapper()->selectRelated($this->entity, $this->relationName);
+        }
+
+        $collection = $this->limit(0, 1)->find();
+
+        if (!count($collection)) {
+            return null;
+        }
+
+        foreach ($collection as $entity) {
+            return $entity;
+        }
+    }
+
+    /**
+     * Get a number of related records.
+     */
+    public function count() : int
+    {
+        return $this->createBuilder()->count();
+    }
+
+    /**
+     * Add JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::join()
+     */
+    public function join(string $relationName, ?string $alias = null, ?array $conditions = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->join($relationName, $alias, $conditions);
+    }
+
+    /**
+     * Add LEFT JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::leftJoin()
+     */
+    public function leftJoin(string $relationName, ?string $alias = null, ?array $conditions = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->leftJoin($relationName, $alias, $conditions);
+    }
+
+    /**
+     * Set DISTINCT parameter.
+     */
+    public function distinct() : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->distinct();
+    }
+
+    /**
+     * Set to return STH collection. Recommended for fetching large number of records.
+     *
+     * @todo Remove.
+     */
+    public function sth() : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->sth();
+    }
+
+    /**
+     * Add a WHERE clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::where()
+     *
+     * @param array|string $keyOrClause
+     * @param ?array|string $value
+     */
+    public function where($keyOrClause = [], $value = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->where($keyOrClause, $value);
+    }
+
+    /**
+     * Add a HAVING clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::having()
+     *
+     * @param array|string $keyOrClause
+     * @param ?array|string $value
+     */
+    public function having($keyOrClause = [], $value = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->having($keyOrClause, $params2);
+    }
+
+    /**
+     * Apply ORDER.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::order()
+     *
+     * @param string|array $orderBy
+      * @param bool|string $direction
+     */
+    public function order($orderBy, $direction = 'ASC') : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->order($orderBy, $direction);
+    }
+
+    /**
+     * Apply OFFSET and LIMIT.
+     */
+    public function limit(?int $offset = null, ?int $limit = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->limit($offset, $limit);
+    }
+
+    /**
+     * Specify SELECT. Which attributes to select. All attributes are selected by default.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::select()
+     *
+     * @param array|string $select
+     */
+    public function select($select, ?string $alias = null) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->select($select, $alias);
+    }
+
+    /**
+     * Specify GROUP BY.
+     */
+    public function groupBy(array $groupBy) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->groupBy($groupBy);
+    }
+
+    /**
+     * @deprecated Use `->select('linkNameMiddle', 'attributeName')` instead.
+     */
+    public function columns(array $columns) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->columns($columns);
+    }
+
+    /**
+     * Apply middle table conditions for a many-to-many relationship.
+     *
+     * @see Espo\ORM\Repository\RDBRelationSelectBuilder::columnsWhere()
+     */
+    public function columnsWhere(array $where) : RDBRelationSelectBuilder
+    {
+        return $this->createBuilder()->columnsWhere($where);
+    }
+
+    protected function processCheckForeignEntity(Entity $entity)
+    {
+        if ($this->foreignEntityType && $this->foreignEntityType !== $entity->getEntityType()) {
+            throw new InvalidArgumentException("Entity type doesn't match an entity type of the relation.");
+        }
+
+        if (!$entity->id) {
+            throw new RuntimeException("Can't use an entity w/o ID.");
+        }
+    }
+
+    public function isRelated(Entity $entity) : bool
+    {
+        if (!$entity->id) {
+            throw new RuntimeException("Can't use an entity w/o ID.");
+        }
+
+        if ($this->isBelongsToParentType()) {
+            return $this->isRelatedBelongsToParent($entity);
+        }
+
+        $this->processCheckForeignEntity($entity);
+
+        return (bool) $this->createBuilder()
+            ->select(['id'])
+            ->where(['id' => $entity->id])
+            ->findOne();
+    }
+
+    protected function isRelatedBelongsToParent(Entity $entity) : bool
+    {
+        $fromEntity = $this->entity;
+
+        $idAttribute = $this->relationName . 'Id';
+        $typeAttribute = $this->relationName . 'Type';
+
+        if (!$fromEntity->has($idAttribute) || !$fromEntity->has($typeAttribute)) {
+            $fromEntity = $this->entityManager->getEntity($fromEntity->getEntityType(), $fromEntity->id);
+        }
+
+        if (!$fromEntity) {
+            return false;
+        }
+
+        return
+            $fromEntity->get($idAttribute) === $entity->id
+            &&
+            $fromEntity->get($typeAttribute) === $entity->getEntityType();
+    }
+
+    /**
+     * Relate with an entity.
+     */
+    public function relate(Entity $entity, ?array $columnData = null, array $options = [])
+    {
+        $this->processCheckForeignEntity($entity);
+
+        $this->beforeRelate($entity, $columnData, $options);
+
+        $result = $this->getMapper()->relateById($this->entity, $this->relationName, $entity->id, $columnData);
+
+        if (!$result) {
+            return;
+        }
+
+        $this->afterRelate($entity, $columnData, $options);
+    }
+
+    /**
+     * Unrelate from an entity.
+     */
+    public function unrelate(Entity $entity, array $options = [])
+    {
+        $this->processCheckForeignEntity($entity);
+
+        $this->beforeUnrelate($entity, $options);
+
+        $result = $this->getMapper()->unrelateById($this->entity, $this->relationName, $entity->id);
+
+        if (!$result) {
+            return;
+        }
+
+        $this->afterUnrelate($entity, $options);
+    }
+
+    public function massRelate(Select $query, array $options = [])
+    {
+        $this->beforeMassRelate($query, $options);
+
+        $this->getMapper()->massRelate($this->entity, $this->relationName, $query);
+
+        $this->afterMassRelate($query, $options);
+    }
+
+    /**
+     * Update relationship columns. For many-to-many relationships.
+     */
+    public function updateColumns(Entity $entity, array $columnData)
+    {
+        $this->processCheckForeignEntity($entity);
+
+        if ($this->relationType !== Entity::MANY_MANY) {
+            throw new RuntimeException("Can't update not many-to-many relation.");
+        }
+
+        $this->getMapper()->updateRelationColumns($this->entity, $this->relationName, $entity->id, $columnData);
+    }
+
+    /**
+     * Get a relationship column value. For many-to-many relationships.
+     *
+     * @return mixed
+     */
+    public function getColumn(Entity $entity, string $column)
+    {
+        $this->processCheckForeignEntity($entity);
+
+        if ($this->relationType !== Entity::MANY_MANY) {
+            throw new RuntimeException("Can't get a column of not many-to-many relation.");
+        }
+
+        return $this->getMapper()->getRelationColumn($this->entity, $this->relationName, $entity->id, $column);
+    }
+
+    protected function beforeRelate(Entity $entity, ?array $columnData, array $options)
+    {
+        $this->hookMediator->beforeRelate($this->entity, $this->relationName, $entity, $columnData, $options);
+    }
+
+    protected function afterRelate(Entity $entity, ?array $columnData, array $options)
+    {
+        $this->hookMediator->afterRelate($this->entity, $this->relationName, $entity, $columnData, $options);
+    }
+
+    protected function beforeUnrelate(Entity $entity, array $options)
+    {
+        $this->hookMediator->beforeUnrelate($this->entity, $this->relationName, $entity, $options);
+    }
+
+    protected function afterUnrelate(Entity $entity, array $options)
+    {
+        $this->hookMediator->afterUnrelate($this->entity, $this->relationName, $entity, $options);
+    }
+
+    protected function beforeMassRelate(Select $query, array $options)
+    {
+        $this->hookMediator->beforeMassRelate($this->entity, $this->relationName, $query, $options);
+    }
+
+    protected function afterMassRelate(Select $query, array $options)
+    {
+        $this->hookMediator->afterMassRelate($this->entity, $this->relationName, $query, $options);
+    }
+}
diff --git a/application/Espo/ORM/Repository/RDBRelationSelectBuilder.php b/application/Espo/ORM/Repository/RDBRelationSelectBuilder.php
new file mode 100644
index 0000000000..08bcc302ce
--- /dev/null
+++ b/application/Espo/ORM/Repository/RDBRelationSelectBuilder.php
@@ -0,0 +1,376 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\Repository;
+
+use Espo\ORM\{
+    Collection,
+    Entity,
+    EntityManager,
+    QueryParams\Select,
+    QueryParams\SelectBuilder,
+    Mapper\Mapper,
+};
+
+use RuntimeException;
+use BadMethodCallException;
+
+/**
+ * Builds select parameters for related records for RDB repository.
+ */
+class RDBRelationSelectBuilder
+{
+    protected $entityManager;
+
+    protected $entity;
+
+    protected $entityType;
+
+    protected $foreignEntityType;
+
+    protected $relationName;
+
+    protected $relationType = null;
+
+    protected $builder = null;
+
+    protected $additionalSelect = [];
+
+    protected $selectIsAdded = false;
+
+    public function __construct(EntityManager $entityManager, Entity $entity, string $relationName, ?Select $query = null)
+    {
+        $this->entityManager = $entityManager;
+
+        $this->entity = $entity;
+
+        $this->relationName = $relationName;
+
+        $this->relationType = $entity->getRelationType($relationName);
+
+        $this->entityType = $entity->getEntityType();
+
+        $this->foreignEntityType = $entity->getRelationParam($relationName, 'entity');
+
+        if ($query) {
+            $this->builder = $this->createSelectBuilder()->clone($query);
+        } else {
+            $this->builder = $this->createSelectBuilder()->from($this->foreignEntityType);
+        }
+    }
+
+    protected function createSelectBuilder() : SelectBuilder
+    {
+        return new SelectBuilder($this->entityManager->getQueryComposer());
+    }
+
+    protected function getMapper() : Mapper
+    {
+        return $this->entityManager->getMapper();
+    }
+
+    /**
+     * Additional middle table columns. Only for many-to-many relationships.
+     *
+     * Usage example:
+     * `['columnName' => 'attributeName']`
+     * Where `attributeName` is a non storable attribute that will be set with a column value.
+     *
+     * @todo Remove? Use attribute definitions to detect a proper select expression (in QueryComposer).
+     * @deprecated Use `->select('middleTable', 'attributeName')` instead.
+     */
+    public function columns(array $columns) : self
+    {
+        if (!count($columns)) {
+            return $this;
+        }
+
+        if ($this->relationType !== Entity::MANY_MANY) {
+            throw new RuntimeException("Can't select relation columns for not many-to-many relationship.");
+        }
+
+        $middleName = lcfirst(
+            $this->entity->getRelationParam($this->relationName, 'relationName')
+        );
+
+        foreach ($columns as $column => $alias) {
+            $this->additionalSelect[] = [
+                $middleName . '.' . $column,
+                $alias,
+            ];
+        }
+
+        return $this;
+    }
+
+    /**
+     * Apply middle table conditions for a many-to-many relationship.
+     *
+     * Usage example:
+     * `->columnsWhere(['column' => $value])`
+     */
+    public function columnsWhere(array $where) : self
+    {
+        if ($this->relationType !== Entity::MANY_MANY) {
+            throw new RuntimeException("Can't add columns where for not many-to-many relationship.");
+        }
+
+        $transformedWhere = $this->applyMiddleAliasToWhere($where);
+
+        $this->where($transformedWhere);
+
+        return $this;
+    }
+
+    protected function applyMiddleAliasToWhere(array $where) : array
+    {
+        $transformedWhere = [];
+
+        $middleName = lcfirst(
+            $this->entity->getRelationParam($this->relationName, 'relationName')
+        );
+
+        foreach ($where as $key => $value) {
+            $transformedKey = $key;
+            $transformedValue = $value;
+
+            if (is_int($key)) {
+                $transformedKey = $key;
+            }
+
+            if (
+                is_string($key) &&
+                strlen($key) &&
+                strpos($key, '.') === false &&
+                $key[0] === strtolower($key[0])
+            ) {
+                $transformedKey = $middleName . '.' . $key;
+            }
+
+            if (is_array($value)) {
+                $transformedValue = $this->applyMiddleAliasToWhere($value);
+            }
+
+            $transformedWhere[$transformedKey] = $transformedValue;
+        }
+
+        return $transformedWhere;
+    }
+
+    protected function addAdditionalSelect()
+    {
+        if (!count($this->additionalSelect)) {
+            return;
+        }
+
+        $select = $this->builder->build()->getSelect();
+
+        if (!count($select)) {
+            $this->builder->select('*');
+        }
+
+        foreach ($this->additionalSelect as $item) {
+            $this->builder->select($item[0], $item[1]);
+        }
+    }
+
+    /**
+     * Find related records by a criteria.
+     */
+    public function find() : Collection
+    {
+        $this->addAdditionalSelect();
+
+        $query = $this->builder->build();
+
+        $related = $this->getMapper()->selectRelated($this->entity, $this->relationName, $query);
+
+        if ($related instanceof Collection) {
+            return $related;
+        }
+
+        $collection = $this->entityManager->getCollectionFactory()->create($this->foreignEntityType);
+        $collection->setAsFetched();
+
+        if ($related instanceof Entity) {
+            $collection[] = $related;
+        }
+
+        return $collection;
+    }
+
+    /**
+     * Find a first related records by a criteria.
+     */
+    public function findOne() : ?Entity
+    {
+        $collection = $this->limit(0, 1)->find();
+
+        if (!count($collection)) {
+            return null;
+        }
+
+        foreach ($collection as $entity) {
+            return $entity;
+        }
+    }
+
+    /**
+     * Get a number of related records that meet criteria.
+     */
+    public function count() : int
+    {
+        $query = $this->builder->build();
+
+        return $this->getMapper()->countRelated($this->entity, $this->relationName, $query);
+    }
+
+
+    /**
+     * Add JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::join()
+     */
+    public function join($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        $this->builder->join($relationName, $alias, $conditions);
+
+        return $this;
+    }
+
+    /**
+     * Add LEFT JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::leftJoin()
+     */
+    public function leftJoin($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        $this->builder->leftJoin($relationName, $alias, $conditions);
+
+        return $this;
+    }
+
+    /**
+     * Set DISTINCT parameter.
+     */
+    public function distinct() : self
+    {
+        $this->builder->distinct();
+
+        return $this;
+    }
+
+    /**
+     * Set to return STH collection. Recommended for fetching large number of records.
+     *
+     * @todo Remove.
+     */
+    public function sth() : self
+    {
+        $this->builder->sth();
+
+        return $this;
+    }
+
+    /**
+     * Add a WHERE clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::where()
+     *
+     * @param array|string $keyOrClause
+     * @param ?array|string $value
+     */
+    public function where($keyOrClause = [], $value = null) : self
+    {
+        $this->builder->where($keyOrClause, $value);
+
+        return $this;
+    }
+
+    /**
+     * Add a HAVING clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::having()
+     */
+    public function having($keyOrClause = [], $value = null) : self
+    {
+        $this->builder->having($keyOrClause, $params2);
+
+        return $this;
+    }
+
+    /**
+     * Apply ORDER.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::order()
+     *
+     * @param string|array $orderBy
+     * @param bool|string $direction
+     */
+    public function order($orderBy, $direction = 'ASC') : self
+    {
+        $this->builder->order($orderBy, $direction);
+
+        return $this;
+    }
+
+    /**
+     * Apply OFFSET and LIMIT.
+     */
+    public function limit(?int $offset = null, ?int $limit = null) : self
+    {
+        $this->builder->limit($offset, $limit);
+
+        return $this;
+    }
+
+    /**
+     * Specify SELECT. Which attributes to select. All attributes are selected by default.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::select()
+     *
+     * @param array|string $select
+     */
+    public function select($select, ?string $alias = null) : self
+    {
+        $this->builder->select($select, $alias);
+
+        return $this;
+    }
+
+    /**
+     * Specify GROUP BY.
+     */
+    public function groupBy(array $groupBy) : self
+    {
+        $this->builder->groupBy($groupBy);
+
+        return $this;
+    }
+}
diff --git a/application/Espo/ORM/Repositories/RDB.php b/application/Espo/ORM/Repository/RDBRepository.php
similarity index 59%
rename from application/Espo/ORM/Repositories/RDB.php
rename to application/Espo/ORM/Repository/RDBRepository.php
index 90930986dd..2a04bdc57a 100644
--- a/application/Espo/ORM/Repositories/RDB.php
+++ b/application/Espo/ORM/Repository/RDBRepository.php
@@ -27,48 +27,51 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM\Repositories;
+namespace Espo\ORM\Repository;
 
 use Espo\ORM\{
     EntityManager,
     EntityFactory,
     Collection,
     Entity,
-    Repository,
-    DB\Mapper,
-    RDBSelectBuilder as RDBSelectBuilder,
+    Mapper\Mapper,
+    QueryParams\Select,
 };
 
 use StdClass;
 use RuntimeException;
+use InvalidArgumentException;
 
-class RDB extends Repository implements Findable, Relatable, Removable
+class RDBRepository extends Repository
 {
     protected $mapper;
 
     private $isTableLocked = false;
 
-    public function __construct(string $entityType, EntityManager $entityManager, EntityFactory $entityFactory)
-    {
+    protected $hookMediator;
+
+    public function __construct(
+        string $entityType, EntityManager $entityManager, EntityFactory $entityFactory, ?HookMediator $hookMediator = null
+    ) {
         $this->entityType = $entityType;
         $this->entityName = $entityType;
 
         $this->entityFactory = $entityFactory;
-        $this->seed = $this->entityFactory->create($entityType);
-        $this->entityClassName = get_class($this->seed);
         $this->entityManager = $entityManager;
+
+        $this->seed = $this->entityFactory->create($entityType);
+
+        $this->hookMediator = $hookMediator ?? (new EmptyHookMediator());
     }
 
     protected function getMapper() : Mapper
     {
-        if (empty($this->mapper)) {
-            $this->mapper = $this->getEntityManager()->getMapper('RDB');
-        }
-        return $this->mapper;
+        return $this->entityManager->getMapper();
     }
 
     /**
      * @deprecated
+     * @todo Remove in 6.0.
      */
     public function handleSelectParams(&$params)
     {
@@ -84,6 +87,7 @@ class RDB extends Repository implements Findable, Relatable, Removable
         if ($entity) {
             $entity->setIsNew(true);
             $entity->populateDefaults();
+
             return $entity;
         }
 
@@ -93,16 +97,17 @@ class RDB extends Repository implements Findable, Relatable, Removable
     /**
      * Fetch an entity by ID.
      */
-    public function getById(string $id, array $params = []) : ?Entity
+    public function getById(string $id) : ?Entity
     {
-        $entity = $this->entityFactory->create($this->entityType);
-        if (!$entity) return null;
+        $select = $this->entityManager->getQueryBuilder()
+            ->select()
+            ->from($this->entityType)
+            ->where([
+                'id' => $id,
+            ])
+            ->build();
 
-        if (empty($params['skipAdditionalSelectParams'])) {
-            $this->handleSelectParams($params);
-        }
-
-        return $this->getMapper()->selectById($entity, $id, $params);
+        return $this->getMapper()->selectOne($select);
     }
 
     public function get(?string $id = null) : ?Entity
@@ -110,19 +115,21 @@ class RDB extends Repository implements Findable, Relatable, Removable
         if (is_null($id)) {
             return $this->getNew();
         }
+
         return $this->getById($id);
     }
 
-    protected function beforeSave(Entity $entity, array $options = [])
-    {
-    }
-
-    protected function afterSave(Entity $entity, array $options = [])
+    protected function processCheckEntity(Entity $entity)
     {
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new RuntimeException("An entity type doesn't match the repository.");
+        }
     }
 
     public function save(Entity $entity, array $options = [])
     {
+        $this->processCheckEntity($entity);
+
         $entity->setAsBeingSaved();
 
         if (empty($options['skipBeforeSave']) && empty($options['skipAll'])) {
@@ -161,117 +168,252 @@ class RDB extends Repository implements Findable, Relatable, Removable
         return $this->getMapper()->restoreDeleted($this->entityType, $id);
     }
 
-    protected function beforeRemove(Entity $entity, array $options = [])
-    {
-    }
-
-    protected function afterRemove(Entity $entity, array $options = [])
+    /**
+     * Get an access point for a specific relation of a record.
+     */
+    public function getRelation(Entity $entity, string $relationName) : RDBRelation
     {
+        return new RDBRelation($this->entityManager, $entity, $relationName, $this->hookMediator);
     }
 
+    /**
+     * Remove a record (mark as deleted).
+     */
     public function remove(Entity $entity, array $options = [])
     {
+        $this->processCheckEntity($entity);
+
         $this->beforeRemove($entity, $options);
+
         $this->getMapper()->delete($entity);
+
         $this->afterRemove($entity, $options);
     }
 
+    /**
+     * @deprecated Use QueryBuilder instead.
+     */
     public function deleteFromDb(string $id, bool $onlyDeleted = false)
     {
         $this->getMapper()->deleteFromDb($this->entityType, $id, $onlyDeleted);
     }
 
-    public function find(array $params = []) : Collection
+    /**
+     * Find records.
+     *
+     * @param $params @deprecated Omit it.
+     */
+    public function find(?array $params = []) : Collection
     {
+        // @todo Remove.
+        if (empty($query['skipAdditionalSelectParams'])) {
+            $this->handleSelectParams($query);
+        }
+
+        return $this->createSelectBuilder()->find($params);
+    }
+
+    /**
+     * Find one record.
+     *
+     * @param $params @deprecated Omit it.
+     */
+    public function findOne(?array $params = []) : ?Entity
+    {
+        // @todo Remove.
         if (empty($params['skipAdditionalSelectParams'])) {
             $this->handleSelectParams($params);
         }
 
-        $collection = $this->getMapper()->select($this->seed, $params);
-
-        return $collection;
-    }
-
-    public function findOne(array $params = []) : ?Entity
-    {
-        unset($params['returnSthCollection']);
-
         $collection = $this->limit(0, 1)->find($params);
 
-        if (count($collection)) {
-            return $collection[0];
+        foreach ($collection as $entity) {
+            return $entity;
         }
 
         return null;
     }
 
-    public function findByQuery(string $sql, ?string $collectionType = null)
+    /**
+     * Find records by a SQL query.
+     */
+    public function findBySql(string $sql) : Collection
     {
-        if (!$collectionType) {
-            $collection = $this->getMapper()->selectByQuery($this->seed, $sql);
-        } else if ($collectionType === EntityManager::STH_COLLECTION) {
-            $collection = $this->getEntityManager()->createSthCollection($this->entityType);
-            $collection->setQuery($sql);
-        }
-
-        return $collection;
+        return $this->getMapper()->selectBySql($this->entityType, $sql);
     }
 
-    public function findRelated(Entity $entity, string $relationName, array $params = [])
+    /**
+     * @deprecated
+     */
+    public function findRelated(Entity $entity, string $relationName, ?array $params = null)
     {
+        $params = $params ?? [];
+
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new InvalidArgumentException("Not supported entity type.");
+        }
+
         if (!$entity->id) {
             return null;
         }
 
-        if ($entity->getRelationType($relationName) === Entity::BELONGS_TO_PARENT) {
-            $entityType = $entity->get($relationName . 'Type');
-        } else {
-            $entityType = $entity->getRelationParam($relationName, 'entity');
-        }
+        $type = $entity->getRelationType($relationName);
+        $entityType = $entity->getRelationParam($relationName, 'entity');
 
         if ($entityType && empty($params['skipAdditionalSelectParams'])) {
-            $this->getEntityManager()->getRepository($entityType)->handleSelectParams($params);
+            $this->entityManager->getRepository($entityType)->handleSelectParams($params);
         }
 
-        $result = $this->getMapper()->selectRelated($entity, $relationName, $params);
+        $additionalColumns = $params['additionalColumns'] ?? [];
+        unset($params['additionalColumns']);
+
+        $additionalColumnsConditions = $params['additionalColumnsConditions'] ?? [];
+        unset($params['additionalColumnsConditions']);
+
+        $select = null;
+
+        if ($entityType) {
+            $params['from'] = $entityType;
+            $select = Select::fromRaw($params);
+        }
+
+        if ($type === Entity::MANY_MANY && count($additionalColumns)) {
+            $select = $this->applyRelationAdditionalColumns($entity, $relationName, $additionalColumns, $select);
+        }
+
+        // @todo Get rid of 'additionalColumnsConditions' usage. Use 'whereClause' instead.
+        if ($type === Entity::MANY_MANY && count($additionalColumnsConditions)) {
+            $select = $this->applyRelationAdditionalColumnsConditions(
+                $entity, $relationName, $additionalColumnsConditions, $select
+            );
+        }
+
+        $result = $this->getMapper()->selectRelated($entity, $relationName, $select);
 
         return $result;
     }
 
-    public function countRelated(Entity $entity, string $relationName, array $params = []) : int
+    /**
+     * @deprecated
+     */
+    public function countRelated(Entity $entity, string $relationName, ?array $params = null) : int
     {
+        $params = $params ?? [];
+
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new InvalidArgumentException("Not supported entity type.");
+        }
+
         if (!$entity->id) {
             return 0;
         }
 
-        $entityType =  $entity->getRelationParam($relationName, 'entity');
+        $type = $entity->getRelationType($relationName);
+        $entityType = $entity->getRelationParam($relationName, 'entity');
 
         if ($entityType && empty($params['skipAdditionalSelectParams'])) {
-            $this->getEntityManager()->getRepository($entityType)->handleSelectParams($params);
+            $this->entityManager->getRepository($entityType)->handleSelectParams($params);
         }
 
-        return intval($this->getMapper()->countRelated($entity, $relationName, $params));
+        $additionalColumnsConditions = $params['additionalColumnsConditions'] ?? [];
+        unset($params['additionalColumnsConditions']);
+
+        if ($type === Entity::MANY_MANY && count($additionalColumnsConditions)) {
+            $select = $this->applyRelationAdditionalColumnsConditions($entity, $relationName, $additionalColumnsConditions, $select);
+        }
+
+        $select = null;
+
+        if ($entityType) {
+            $params['from'] = $entityType;
+            $select = Select::fromRaw($params);
+        }
+
+        return (int) $this->getMapper()->countRelated($entity, $relationName, $select);
     }
 
+    protected function applyRelationAdditionalColumns(
+        Entity $entity, string $relationName, array $columns, Select $select
+    ) : Select {
+        if (empty($columns)) {
+            return $select;
+        }
+
+        $middleName = lcfirst($entity->getRelationParam($relationName, 'relationName'));
+
+        $selectItemList = $select->getSelect();
+
+        if (empty($selectItemList)) {
+            $selectItemList[] = '*';
+        }
+
+        foreach ($columns as $column => $alias) {
+            $selectItemList[] = [
+                $middleName . '.' . $column,
+                $alias
+            ];
+        }
+
+        $select = $this->entityManager->getQueryBuilder()
+            ->clone($select)
+            ->select($selectItemList)
+            ->build();
+
+        return $select;
+    }
+
+    protected function applyRelationAdditionalColumnsConditions(
+        Entity $entity, string $relationName, array $conditions, Select $select
+    ) : Select {
+        if (empty($conditions)) {
+            return $select;
+        }
+
+        $middleName = lcfirst($entity->getRelationParam($relationName, 'relationName'));
+
+        $builder = $this->entityManager->getQueryBuilder()->clone($select);
+
+        foreach ($conditions as $column => $value) {
+            $builder->where(
+                $middleName . '.' . $column,
+                $value
+            );
+        }
+
+        return $builder->build();
+    }
+
+    /**
+     * @deprecated
+     */
     public function isRelated(Entity $entity, string $relationName, $foreign) : bool
     {
         if (!$entity->id) {
             return false;
         }
 
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new InvalidArgumentException("Not supported entity type.");
+        }
+
         if ($foreign instanceof Entity) {
             $id = $foreign->id;
         } else if (is_string($foreign)) {
             $id = $foreign;
         } else {
+            throw new RuntimeException("Bad 'foreign' value.");
+        }
+
+        if (!$id) {
             return false;
         }
 
-        if (!$id) return false;
-
         if ($entity->getRelationType($relationName) === Entity::BELONGS_TO) {
             $foreignEntityType = $entity->getRelationParam($relationName, 'entity');
-            if (!$foreignEntityType) return false;
+
+            if (!$foreignEntityType) {
+                return false;
+            }
 
             $foreignId = $entity->get($relationName . 'Id');
 
@@ -282,24 +424,33 @@ class RDB extends Repository implements Findable, Relatable, Removable
                 }
             }
 
-            if (!$foreignId) return false;
+            if (!$foreignId) {
+                return false;
+            }
 
-            $foreignEntity = $this->getEntityManager()->getRepository($foreignEntityType)->select(['id'])->where([
-                'id' => $foreignId,
-            ])->findOne();
+            $foreignEntity = $this->entityManager->getRepository($foreignEntityType)
+                ->select(['id'])
+                ->where(['id' => $foreignId])
+                ->findOne();
 
-            if (!$foreignEntity) return false;
+            if (!$foreignEntity) {
+                return false;
+            }
 
             return $foreignEntity->id === $id;
         }
 
+        // @todo Use related builder.
         return (bool) $this->countRelated($entity, $relationName, [
             'whereClause' => [
                 'id' => $id,
-            ]
+            ],
         ]);
     }
 
+    /**
+     * @deprecated
+     */
     public function relate(Entity $entity, string $relationName, $foreign, $columnData = null, array $options = [])
     {
         if (!$entity->id) {
@@ -307,7 +458,11 @@ class RDB extends Repository implements Findable, Relatable, Removable
         }
 
         if (! $foreign instanceof Entity && !is_string($foreign)) {
-            throw new RuntimeException("Bad foreign value.");
+            throw new RuntimeException("Bad 'foreign' value.");
+        }
+
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new InvalidArgumentException("Not supported entity type.");
         }
 
         $this->beforeRelate($entity, $relationName, $foreign, $columnData, $options);
@@ -350,6 +505,9 @@ class RDB extends Repository implements Findable, Relatable, Removable
         return $result;
     }
 
+    /**
+     * @deprecated
+     */
     public function unrelate(Entity $entity, string $relationName, $foreign, array $options = [])
     {
         if (!$entity->id) {
@@ -360,6 +518,10 @@ class RDB extends Repository implements Findable, Relatable, Removable
             throw new RuntimeException("Bad foreign value.");
         }
 
+        if ($entity->getEntityType() !== $this->entityType) {
+            throw new InvalidArgumentException("Not supported entity type.");
+        }
+
         $this->beforeUnrelate($entity, $relationName, $foreign, $options);
 
         $beforeMethodName = 'beforeUnrelate' . ucfirst($relationName);
@@ -395,6 +557,9 @@ class RDB extends Repository implements Findable, Relatable, Removable
         return $result;
     }
 
+    /**
+     * @deprecated
+     */
     public function getRelationColumn(Entity $entity, string $relationName, string $foreignId, string $column)
     {
         return $this->getMapper()->getRelationColumn($entity, $relationName, $foreignId, $column);
@@ -425,7 +590,7 @@ class RDB extends Repository implements Findable, Relatable, Removable
     }
 
     /**
-     * Update relationship columns.
+     * @deprecated
      */
     public function updateRelation(Entity $entity, string $relationName, $foreign, $columnData)
     {
@@ -451,9 +616,12 @@ class RDB extends Repository implements Findable, Relatable, Removable
             throw new RuntimeException("Bad foreign value.");
         }
 
-        return $this->getMapper()->updateRelation($entity, $relationName, $id, $columnData);
+        return $this->getMapper()->updateRelationColumns($entity, $relationName, $id, $columnData);
     }
 
+    /**
+     * @deprecated
+     */
     public function massRelate(Entity $entity, string $relationName, array $params = [], array $options = [])
     {
         if (!$entity->id) {
@@ -462,54 +630,76 @@ class RDB extends Repository implements Findable, Relatable, Removable
 
         $this->beforeMassRelate($entity, $relationName, $params, $options);
 
-        $this->getMapper()->massRelate($entity, $relationName, $params);
+        $select = Select::fromRaw($params);
+
+        $this->getMapper()->massRelate($entity, $relationName, $select);
 
         $this->afterMassRelate($entity, $relationName, $params, $options);
     }
 
+    /**
+     * @param $params @deprecated Omit it.
+     */
     public function count(array $params = []) : int
     {
-        if (empty($params['skipAdditionalSelectParams'])) {
+        // @todo Remove it.
+        if (is_array($params) && empty($params['skipAdditionalSelectParams'])) {
             $this->handleSelectParams($params);
         }
 
-        $count = $this->getMapper()->count($this->seed, $params);
-
-        return intval($count);
+        return $this->createSelectBuilder()->count($params);
     }
 
-    public function max(string $attribute, array $params = [])
+    /**
+     * Get a max value.
+     *
+     * @return int|float
+     */
+    public function max(string $attribute)
     {
-        return $this->getMapper()->max($this->seed, $params, $attribute);
+        return $this->createSelectBuilder()->max($attribute);
     }
 
-    public function min(string $attribute, array $params = [])
+    /**
+     * Get a min value.
+     *
+     * @return int|float
+     */
+    public function min(string $attribute)
     {
-        return $this->getMapper()->min($this->seed, $params, $attribute);
+        return $this->createSelectBuilder()->min($attribute);
     }
 
-    public function sum(string $attribute, array $params = [])
+    /**
+     * Get a sum value.
+     *
+     * @return int|float
+     */
+    public function sum(string $attributel)
     {
-        return $this->getMapper()->sum($this->seed, $params, $attribute);
+        return $this->createSelectBuilder()->sum($attribute);
+    }
+
+    /**
+     * Clone an existing query for a further modification and usage by 'find' or 'count' methods.
+     */
+    public function clone(Select $query) : RDBSelectBuilder
+    {
+        if ($this->entityType !== $query->getFrom()) {
+            throw new RuntimeException("Can't clone a query of a different entity type.");
+        }
+
+        $builder = new RDBSelectBuilder($this->entityManager, $this->entityType, $query);
+
+        return $builder;
+
+        //return $builder->clone($query);
     }
 
     /**
      * Add JOIN.
      *
-     * @param string|array $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
-     *
-     * Usage options:
-     * * `join(string $relationName)`
-     * * `join(array $joinDefinitionList)`
-     *
-     * Usage examples:
-     * ```
-     * ->join($relationName)
-     * ->join($relationName, $alias, $conditions)
-     * ->join([$relationName1, $relationName2, ...])
-     * ->join([[$relationName, $alias], ...])
-     * ->join([[$relationName, $alias, $conditions], ...])
-     * ```
+     * @see Espo\ORM\QueryParams\SelectBuilder::join()
      */
     public function join($relationName, ?string $alias = null, ?array $conditions = null) : RDBSelectBuilder
     {
@@ -519,9 +709,7 @@ class RDB extends Repository implements Findable, Relatable, Removable
     /**
      * Add LEFT JOIN.
      *
-     * @param string|array $relationName A relationName or table. A relationName is in camelCase, a table is in CamelCase.
-     *
-     * This method works the same way as `join` method.
+     * @see Espo\ORM\QueryParams\SelectBuilder::leftJoin()
      */
     public function leftJoin($relationName, ?string $alias = null, ?array $conditions = null) : RDBSelectBuilder
     {
@@ -538,6 +726,8 @@ class RDB extends Repository implements Findable, Relatable, Removable
 
     /**
      * Set to return STH collection. Recommended fetching large number of records.
+     *
+     * @todo Remove.
      */
     public function sth() : RDBSelectBuilder
     {
@@ -547,9 +737,7 @@ class RDB extends Repository implements Findable, Relatable, Removable
     /**
      * Add a WHERE clause.
      *
-     * Two usage options:
-     * * `where(array $whereClause)`
-     * * `where(string $key, string $value)`
+     * @see Espo\ORM\QueryParams\SelectBuilder::where()
      */
     public function where($param1 = [], $param2 = null) : RDBSelectBuilder
     {
@@ -559,9 +747,7 @@ class RDB extends Repository implements Findable, Relatable, Removable
     /**
      * Add a HAVING clause.
      *
-     * Two usage options:
-     * * `having(array $havingClause)`
-     * * `having(string $key, string $value)`
+     * @see Espo\ORM\QueryParams\SelectBuilder::having()
      */
     public function having($param1 = [], $param2 = null) : RDBSelectBuilder
     {
@@ -589,10 +775,14 @@ class RDB extends Repository implements Findable, Relatable, Removable
 
     /**
      * Specify SELECT. Which attributes to select. All attributes are selected by default.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::select()
+     *
+     * @param array|string $select
      */
-    public function select(array $select) : RDBSelectBuilder
+    public function select($select = [], ?string $alias = null) : RDBSelectBuilder
     {
-        return $this->createSelectBuilder()->select($select);
+        return $this->createSelectBuilder()->select($select, $alias);
     }
 
     /**
@@ -605,19 +795,21 @@ class RDB extends Repository implements Findable, Relatable, Removable
 
     protected function getPDO()
     {
-        return $this->getEntityManager()->getPDO();
+        return $this->entityManager->getPDO();
     }
 
     protected function lockTable()
     {
-        $tableName = $this->getEntityManager()->getQuery()->toDb($this->entityType);
+        $tableName = $this->entityManager->getQueryComposer()->toDb($this->entityType);
 
+        // @todo Use Query to get SQL. Transaction query params.
         $this->getPDO()->query("LOCK TABLES `{$tableName}` WRITE");
         $this->isTableLocked = true;
     }
 
     protected function unlockTable()
     {
+        // @todo Use Query to get SQL.
         $this->getPDO()->query("UNLOCK TABLES");
         $this->isTableLocked = false;
     }
@@ -629,8 +821,28 @@ class RDB extends Repository implements Findable, Relatable, Removable
 
     protected function createSelectBuilder() : RDBSelectBuilder
     {
-        $builder = new RDBSelectBuilder($this->getEntityManager());
-        $builder->from($this->getEntityType());
+        $builder = new RDBSelectBuilder($this->entityManager, $this->entityType);
+
         return $builder;
     }
+
+    protected function beforeSave(Entity $entity, array $options = [])
+    {
+        $this->hookMediator->beforeSave($entity, $options);
+    }
+
+    protected function afterSave(Entity $entity, array $options = [])
+    {
+        $this->hookMediator->afterSave($entity, $options);
+    }
+
+    protected function beforeRemove(Entity $entity, array $options = [])
+    {
+        $this->hookMediator->beforeRemove($entity, $options);
+    }
+
+    protected function afterRemove(Entity $entity, array $options = [])
+    {
+        $this->hookMediator->afterRemove($entity, $options);
+    }
 }
diff --git a/application/Espo/ORM/Repository/RDBSelectBuilder.php b/application/Espo/ORM/Repository/RDBSelectBuilder.php
new file mode 100644
index 0000000000..6e3753746d
--- /dev/null
+++ b/application/Espo/ORM/Repository/RDBSelectBuilder.php
@@ -0,0 +1,336 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\ORM\Repository;
+
+use Espo\ORM\{
+    Collection,
+    Entity,
+    EntityManager,
+    QueryParams\Select,
+    QueryParams\SelectBuilder,
+    Mapper\Mapper,
+};
+
+use RuntimeException;
+
+/**
+ * Builds select parameters for an RDB repository. Contains 'find' methods.
+ */
+class RDBSelectBuilder
+{
+    protected $entityManager;
+
+    protected $builder;
+
+    protected $repository = null;
+
+    protected $entityType = null;
+
+    public function __construct(EntityManager $entityManager, string $entityType, ?Select $query = null)
+    {
+        $this->entityManager = $entityManager;
+
+        $this->entityType = $entityType;
+
+        $this->repository = $this->entityManager->getRepository($entityType);
+
+        if ($query && $query->getFrom() !== $entityType) {
+            throw new RuntimeException("SelectBuilder: Passed query doesn't match the entity type.");
+        }
+
+        $this->builder = new SelectBuilder($entityManager->getQueryComposer());
+
+        if ($query) {
+            $this->builder->clone($query);
+        }
+
+        if (!$query) {
+            $this->builder->from($entityType);
+        }
+    }
+
+    protected function getMapper() : Mapper
+    {
+        return $this->entityManager->getMapper();
+    }
+
+    /**
+     * @param $params @deprecated. Omit it.
+     */
+    public function find(?array $params = null) : Collection
+    {
+        $query = $this->getMergedParams($params);
+
+        return $this->getMapper()->select($query);
+    }
+
+    /**
+     * @param $params @deprecated. Omit it.
+     */
+    public function findOne(?array $params = null) : ?Entity
+    {
+        if ($params !== null) {
+            $query = $this->getMergedParams($params);
+
+            $collection = $this->repository->clone($query)->limit(0, 1)->find();
+        } else {
+            $collection = $this->limit(0, 1)->find();
+        }
+
+        foreach ($collection as $entity) {
+            return $entity;
+        }
+
+        return null;
+    }
+
+    /**
+     * Get a number of records.
+     *
+     * @param $params @deprecated. Omit it.
+     */
+    public function count(?array $params = null) : int
+    {
+        $query = $this->getMergedParams($params);
+
+        return $this->getMapper()->count($query);
+    }
+
+    /**
+     * Get a max value.
+     *
+     * @return int|float
+     */
+    public function max(string $attribute)
+    {
+        $query = $this->builder->build();
+
+        return $this->getMapper()->max($query, $attribute);
+    }
+
+    /**
+     * Get a min value.
+     *
+     * @return int|float
+     */
+    public function min(string $attribute)
+    {
+        $query = $this->builder->build();
+
+        return $this->getMapper()->min($query, $attribute);
+    }
+
+    /**
+     * Get a sum value.
+     *
+     * @return int|float
+     */
+    public function sum(string $attribute)
+    {
+        $query = $this->builder->build();
+
+        return $this->getMapper()->sum($query, $attribute);
+    }
+
+    /**
+     * Add JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::join()
+     */
+    public function join($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        $this->builder->join($relationName, $alias, $conditions);
+
+        return $this;
+    }
+
+    /**
+     * Add LEFT JOIN.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::leftJoin()
+     */
+    public function leftJoin($relationName, ?string $alias = null, ?array $conditions = null) : self
+    {
+        $this->builder->leftJoin($relationName, $alias, $conditions);
+
+        return $this;
+    }
+
+    /**
+     * Set DISTINCT parameter.
+     */
+    public function distinct() : self
+    {
+        $this->builder->distinct();
+
+        return $this;
+    }
+
+    /**
+     * Set to return STH collection. Recommended for fetching large number of records.
+     *
+     * @todo Remove.
+     */
+    public function sth() : self
+    {
+        $this->builder->sth();
+
+        return $this;
+    }
+
+    /**
+     * Add a WHERE clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::where()
+     */
+    public function where($keyOrClause = [], $value = null) : self
+    {
+        $this->builder->where($keyOrClause, $value);
+
+        return $this;
+    }
+
+    /**
+     * Add a HAVING clause.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::having()
+     */
+    public function having($keyOrClause = [], $value = null) : self
+    {
+        $this->builder->having($keyOrClause, $value);
+
+        return $this;
+    }
+
+    /**
+     * Apply ORDER.
+     *
+     * @param string|array $orderBy An attribute to order by or order definitions as an array.
+     * @param bool|string $direction TRUE for DESC order.
+     */
+    public function order($orderBy = 'id', $direction = 'ASC') : self
+    {
+        $this->builder->order($orderBy, $direction);
+
+        return $this;
+    }
+
+    /**
+     * Apply OFFSET and LIMIT.
+     */
+    public function limit(?int $offset = null, ?int $limit = null) : self
+    {
+        $this->builder->limit($offset, $limit);
+
+        return $this;
+    }
+
+    /**
+     * Specify SELECT. Which attributes to select. All attributes are selected by default.
+     *
+     * @see Espo\ORM\QueryParams\SelectBuilder::select()
+     *
+     * @param array|string $select
+     */
+    public function select($select, ?string $alias = null) : self
+    {
+        $this->builder->select($select, $alias);
+
+        return $this;
+    }
+
+    /**
+     * Specify GROUP BY.
+     */
+    public function groupBy(array $groupBy) : self
+    {
+        $this->builder->groupBy($groupBy);
+
+        return $this;
+    }
+
+    /**
+     * For backward compatibility.
+     * @todo Remove.
+     */
+    protected function getMergedParams(?array $params = null) : Select
+    {
+        if (!$params || empty($params)) {
+            return $this->builder->build();
+        }
+
+        $params = $params ?? [];
+
+        $builtParams = $this->builder->build()->getRawParams();
+
+        $whereClause = $builtParams['whereClause'] ?? [];
+        $havingClause = $builtParams['havingClause'] ?? [];
+        $joins = $builtParams['joins'] ?? [];
+        $leftJoins = $builtParams['leftJoins'] ?? [];
+
+        if (!empty($params['whereClause'])) {
+            unset($builtParams['whereClause']);
+            if (count($whereClause)) {
+                $params['whereClause'][] = $whereClause;
+            }
+        }
+
+        if (!empty($params['havingClause'])) {
+            unset($builtParams['havingClause']);
+            if (count($havingClause)) {
+                $params['havingClause'][] = $havingClause;
+            }
+        }
+
+        if (empty($params['whereClause'])) {
+            unset($params['whereClause']);
+        }
+
+        if (empty($params['havingClause'])) {
+            unset($params['havingClause']);
+        }
+
+        if (!empty($params['leftJoins']) && !empty($leftJoins)) {
+            foreach ($leftJoins as $j) {
+                $params['leftJoins'][] = $j;
+            }
+        }
+
+        if (!empty($params['joins']) && !empty($joins)) {
+            foreach ($joins as $j) {
+                $params['joins'][] = $j;
+            }
+        }
+
+        $params = array_replace_recursive($builtParams, $params);
+
+        return Select::fromRaw($params);
+    }
+}
diff --git a/application/Espo/ORM/Repository.php b/application/Espo/ORM/Repository/Repository.php
similarity index 92%
rename from application/Espo/ORM/Repository.php
rename to application/Espo/ORM/Repository/Repository.php
index 9fd3818dec..dd7af1f1c3 100644
--- a/application/Espo/ORM/Repository.php
+++ b/application/Espo/ORM/Repository/Repository.php
@@ -27,7 +27,13 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM;
+namespace Espo\ORM\Repository;
+
+use Espo\ORM\{
+    Entity,
+    EntityManager,
+    EntityFactory,
+};
 
 /**
  * An access point for fetching and storing records.
@@ -40,17 +46,16 @@ abstract class Repository
 
     protected $seed;
 
-    protected $entityClassName;
-
     protected $entityType;
 
     public function __construct(string $entityType, EntityManager $entityManager, EntityFactory $entityFactory)
     {
         $this->entityType = $entityType;
+
         $this->entityFactory = $entityFactory;
-        $this->seed = $this->entityFactory->create($entityType);
-        $this->entityClassName = get_class($this->seed);
         $this->entityManager = $entityManager;
+
+        $this->seed = $this->entityFactory->create($entityType);
     }
 
     protected function getEntityFactory() : EntityFactory
@@ -69,12 +74,12 @@ abstract class Repository
     }
 
     /**
-     * Get entity. If $id is NULL, a new entity is returned.
+     * Get an entity. If $id is NULL, a new entity is returned.
      */
     abstract public function get(?string $id = null) : ?Entity;
 
     /**
-     * Store entity.
+     * Store an entity.
      */
     abstract public function save(Entity $entity);
 }
diff --git a/application/Espo/ORM/RepositoryFactory.php b/application/Espo/ORM/Repository/RepositoryFactory.php
similarity index 94%
rename from application/Espo/ORM/RepositoryFactory.php
rename to application/Espo/ORM/Repository/RepositoryFactory.php
index 4c369a8d29..58973fd9b0 100644
--- a/application/Espo/ORM/RepositoryFactory.php
+++ b/application/Espo/ORM/Repository/RepositoryFactory.php
@@ -27,9 +27,9 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-namespace Espo\ORM;
+namespace Espo\ORM\Repository;
 
 interface RepositoryFactory
 {
-    public function create(string $name) : object;
+    public function create(string $name) : Repository;
 }
diff --git a/application/Espo/ORM/SthCollection.php b/application/Espo/ORM/SthCollection.php
index 009c56b8df..f04cee5d60 100644
--- a/application/Espo/ORM/SthCollection.php
+++ b/application/Espo/ORM/SthCollection.php
@@ -29,103 +29,136 @@
 
 namespace Espo\ORM;
 
+use Espo\ORM\{
+    QueryParams\Select as SelectQuery,
+    QueryComposer\QueryComposer as QueryComposer,
+};
+
+use IteratorAggregate;
+use Countable;
+use PDO;
+
 /**
  * Reasonable to use when selecting a large number of records.
  * It doesn't allocate a memory for every entity.
  * Entities are fetched on each iteration while traversing a collection.
+ *
+ * STH stands for Statement Handle.
  */
-class SthCollection implements \IteratorAggregate, Collection
+class SthCollection implements Collection, IteratorAggregate, Countable
 {
-    protected $entityManager = null;
+    protected $entityManager;
 
     protected $entityType;
 
-    protected $selectParams = null;
+    protected $query = null;
 
     private $sth = null;
 
     private $sql = null;
 
-    protected $isFetched = false;
+    protected $entityList = [];
 
-    public function __construct(string $entityType, EntityManager $entityManager = null, array $selectParams = [])
+    protected function __construct(EntityManager $entityManager)
     {
-        $this->selectParams = $selectParams;
-        $this->entityType = $entityType;
         $this->entityManager = $entityManager;
     }
 
-    protected function getQuery()
+    protected function getQueryComposer() : QueryComposer
     {
-        return $this->entityManager->getQuery();
+        return $this->entityManager->getQueryComposer();
     }
 
-    protected function getPdo()
-    {
-        return $this->entityManager->getPdo();
-    }
-
-    protected function getEntityFactory()
+    protected function getEntityFactory() : EntityFactory
     {
         return $this->entityManager->getEntityFactory();
     }
 
-    /**
-     * Get select parameters.
-     */
-    public function setSelectParams(array $selectParams)
-    {
-        $this->selectParams = $selectParams;
-    }
-
-    /**
-     * Set an SQL query.
-     */
-    public function setQuery(?string $sql)
+    protected function setSql(string $sql)
     {
         $this->sql = $sql;
     }
 
-    /**
-     * Run an SQL query.
-     */
-    public function executeQuery()
+    protected function getPDO() : PDO
     {
-        if ($this->sql) {
-            $sql = $this->sql;
-        } else {
-            $sql = $this->getQuery()->createSelectQuery($this->entityType, $this->selectParams);
-        }
-        $sth = $this->getPdo()->prepare($sql);
+        return $this->entityManager->getPDO();
+    }
+
+    protected function executeQuery()
+    {
+        $sql = $this->getSql();
+
+        $sth = $this->getPDO()->prepare($sql);
+
         $sth->execute();
 
         $this->sth = $sth;
     }
 
+    protected function getSql() : string
+    {
+        if (!$this->sql) {
+            $this->sql = $this->getQueryComposer()->compose($this->getQuery());
+        }
+
+        return $this->sql;
+    }
+
+    protected function getQuery() : SelectQuery
+    {
+        return $this->query;
+    }
+
     public function getIterator()
     {
         return (function () {
             if (isset($this->sth)) {
                 $this->sth->execute();
             }
+
             while ($row = $this->fetchRow()) {
                 $entity = $this->getEntityFactory()->create($this->entityType);
+
                 $entity->set($row);
                 $entity->setAsFetched();
+
                 $this->prepareEntity($entity);
+
+                $this->entityList[] = $entity;
+
                 yield $entity;
             }
         })();
     }
 
-    protected function fetchRow()
+    protected function executeQueryIfNotExecuted()
     {
         if (!$this->sth) {
             $this->executeQuery();
         }
+    }
+
+    protected function fetchRow()
+    {
+        $this->executeQueryIfNotExecuted();
+
         return $this->sth->fetch(\PDO::FETCH_ASSOC);
     }
 
+    public function count() : int
+    {
+        $this->executeQueryIfNotExecuted();
+
+        $rowCount = $this->sth->rowCount();
+
+        // MySQL may not return a row count for select queries.
+        if ($rowCount) {
+            return $rowCount;
+        }
+
+        return count($this->getValueMapList());
+    }
+
     protected function prepareEntity(Entity $entity)
     {
     }
@@ -152,28 +185,13 @@ class SthCollection implements \IteratorAggregate, Collection
         return $this->toArray(true);
     }
 
-    /**
-     * Mark as fetched from DB.
-     */
-    public function setAsFetched()
-    {
-        $this->isFetched = true;
-    }
 
     /**
-     * Mark as not fetched from DB.
-     */
-    public function setAsNotFetched()
-    {
-        $this->isFetched = false;
-    }
-
-    /**
-     * Is fetched from DB.
+     * Whether Is fetched from DB. SthCollection is always fetched.
      */
     public function isFetched() : bool
     {
-        return $this->isFetched;
+        return true;
     }
 
     /**
@@ -183,4 +201,24 @@ class SthCollection implements \IteratorAggregate, Collection
     {
         return $this->entityType;
     }
+
+    public static function fromQuery(SelectQuery $query, EntityManager $entityManager) : self
+    {
+        $obj = new self($entityManager);
+
+        $obj->entityType = $query->getFrom();
+        $obj->query = $query;
+
+        return $obj;
+    }
+
+    public static function fromSql(string $entityType, string $sql, EntityManager $entityManager) : self
+    {
+        $obj = new self($entityManager);
+
+        $obj->entityType = $entityType;
+        $obj->sql = $sql;
+
+        return $obj;
+    }
 }
diff --git a/application/Espo/Repositories/EmailAddress.php b/application/Espo/Repositories/EmailAddress.php
index 11f17805bb..0b989456ee 100644
--- a/application/Espo/Repositories/EmailAddress.php
+++ b/application/Espo/Repositories/EmailAddress.php
@@ -94,13 +94,13 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
 
         $emailAddressList = $this
             ->select(['name', 'lower', 'invalid', 'optOut', ['ee.primary', 'primary']])
-            ->join([[
+            ->join(
                 'EntityEmailAddress',
                 'ee',
                 [
                     'ee.emailAddressId:' => 'id',
                 ]
-            ]])
+            )
             ->where([
                 'ee.entityId' => $entity->id,
                 'ee.entityType' => $entity->getEntityType(),
@@ -249,10 +249,9 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
     public function getEntityByAddress(
         string $address, ?string $entityType = null, array $order = ['User', 'Contact', 'Lead', 'Account']
     ) : ?Entity {
-        $selectBuilder = $this->getEntityManager()->createSelectBuilder();
+        $selectBuilder = $this->getEntityManager()->getRepository('EntityEmailAddress')->select();
 
         $selectBuilder
-            ->from('EntityEmailAddress')
             ->select(['entityType', 'entityId'])
             ->sth()
             ->join('EmailAddress', 'ea', ['ea.id:' => 'emailAddressId', 'ea.deleted' => 0])
@@ -262,7 +261,6 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
                 ['primary', 'DESC'],
             ]);
 
-
         if ($entityType) {
             $selectBuilder->where('entityType=', $entityType);
         }
@@ -290,8 +288,6 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
 
     public function storeEntityEmailAddressData(Entity $entity)
     {
-        $pdo = $this->getEntityManager()->getPDO();
-
         $emailAddressValue = $entity->get('emailAddress');
         if (is_string($emailAddressValue)) {
             $emailAddressValue = trim($emailAddressValue);
@@ -410,17 +406,21 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
 
         foreach ($toRemoveList as $address) {
             $emailAddress = $this->getByAddress($address);
-            if ($emailAddress) {
-                $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('EntityEmailAddress', [
-                    'whereClause' => [
-                        'entityId' => $entity->id,
-                        'entityType' => $entity->getEntityType(),
-                        'emailAddressId' => $emailAddress->id,
-                    ],
-                ]);
-                $sth = $pdo->prepare($sql);
-                $sth->execute();
+            if (!$emailAddress) {
+                continue;
             }
+
+            $delete = $this->getEntityManager()->getQueryBuilder()
+                ->delete()
+                ->from('EntityEmailAddress')
+                ->where([
+                    'entityId' => $entity->id,
+                    'entityType' => $entity->getEntityType(),
+                    'emailAddressId' => $emailAddress->id,
+                ])
+                ->build();
+
+            $this->getEntityManager()->getQueryExecutor()->run($delete);
         }
 
         foreach ($toUpdateList as $address) {
@@ -496,8 +496,10 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
             $emailAddress = $this->getByAddress($primary);
 
             if ($emailAddress) {
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityEmailAddress')
+                    ->set(['primary' => false])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -506,10 +508,12 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => false]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
 
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityEmailAddress')
+                    ->set(['primary' => true])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -518,7 +522,7 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => true]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
             }
         }
 
@@ -537,8 +541,6 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
     {
         if (!$entity->has('emailAddress')) return;
 
-        $pdo = $this->getEntityManager()->getPDO();
-
         $emailAddressValue = $entity->get('emailAddress');
         if (is_string($emailAddressValue)) {
             $emailAddressValue = trim($emailAddressValue);
@@ -574,8 +576,10 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
                     $this->markAddressOptedOut($emailAddressValue, !!$entity->get('emailAddressIsOptedOut'));
                 }
 
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityEmailAddress')
+                    ->set(['primary' => true])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -583,7 +587,7 @@ class EmailAddress extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => true]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
 
             } else {
                 if (
diff --git a/application/Espo/Repositories/Import.php b/application/Espo/Repositories/Import.php
index 59f6c99890..b8a8b9cab9 100644
--- a/application/Espo/Repositories/Import.php
+++ b/application/Espo/Repositories/Import.php
@@ -29,11 +29,14 @@
 
 namespace Espo\Repositories;
 
-use Espo\ORM\Entity;
+use Espo\ORM\{
+    Entity,
+    Collection,
+};
 
 class Import extends \Espo\Core\Repositories\Database
 {
-    public function findRelated(Entity $entity, string $relationName, array $params = []) : \Traversable
+    public function findRelated(Entity $entity, string $relationName, ?array $params = [])
     {
         $entityType = $entity->get('entityType');
 
@@ -76,7 +79,7 @@ class Import extends \Espo\Core\Repositories\Database
         ];
     }
 
-    public function countRelated(Entity $entity, string $relationName, array $params = []) : int
+    public function countRelated(Entity $entity, string $relationName, ?array $params = null) : int
     {
         $entityType = $entity->get('entityType');
 
@@ -94,13 +97,15 @@ class Import extends \Espo\Core\Repositories\Database
             }
         }
 
-        $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('ImportEntity', [
-            'whereClause' => [
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
+            ->from('ImportEntity')
+            ->where([
                 'importId' => $entity->id,
-            ]
-        ]);
+            ])
+            ->build();
 
-        $this->getEntityManager()->getPDO()->query($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
 
         parent::afterRemove($entity, $options);
     }
diff --git a/application/Espo/Repositories/PhoneNumber.php b/application/Espo/Repositories/PhoneNumber.php
index 6e7efd2d06..76f34e927c 100644
--- a/application/Espo/Repositories/PhoneNumber.php
+++ b/application/Espo/Repositories/PhoneNumber.php
@@ -92,13 +92,13 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
 
         $numberList = $this
             ->select(['name', 'type', 'invalid', 'optOut', ['en.primary', 'primary']])
-            ->join([[
+            ->join(
                 'EntityPhoneNumber',
                 'en',
                 [
                     'en.phoneNumberId:' => 'id',
                 ]
-            ]])
+            )
             ->where([
                 'en.entityId' => $entity->id,
                 'en.entityType' => $entity->getEntityType(),
@@ -211,8 +211,6 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
 
     protected function storeEntityPhoneNumberData(Entity $entity)
     {
-        $pdo = $this->getEntityManager()->getPDO();
-
         $phoneNumberValue = $entity->get('phoneNumber');
         if (is_string($phoneNumberValue)) {
             $phoneNumberValue = trim($phoneNumberValue);
@@ -335,17 +333,21 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
 
         foreach ($toRemoveList as $number) {
             $phoneNumber = $this->getByNumber($number);
-            if ($phoneNumber) {
-                $sql = $this->getEntityManager()->getQuery()->createDeleteQuery('EntityPhoneNumber', [
-                    'whereClause' => [
-                        'entityId' => $entity->id,
-                        'entityType' => $entity->getEntityType(),
-                        'phoneNumberId' => $phoneNumber->id,
-                    ],
-                ]);
-                $sth = $pdo->prepare($sql);
-                $sth->execute();
+            if (!$phoneNumber) {
+                continue;
             }
+
+            $delete = $this->getEntityManager()->getQueryBuilder()
+                ->delete()
+                ->from('EntityPhoneNumber')
+                ->where([
+                    'entityId' => $entity->id,
+                    'entityType' => $entity->getEntityType(),
+                    'phoneNumberId' => $phoneNumber->id,
+                ])
+                ->build();
+
+            $this->getEntityManager()->getQueryExecutor()->run($delete);
         }
 
         foreach ($toUpdateList as $number) {
@@ -422,10 +424,12 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
 
         if ($primary) {
             $phoneNumber = $this->getByNumber($primary);
-            if ($phoneNumber) {
 
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+            if ($phoneNumber) {
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityPhoneNumber')
+                    ->set(['primary' => false])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -434,10 +438,12 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => false]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
 
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityPhoneNumber')
+                    ->set(['primary' => true])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -446,7 +452,7 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => true]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
             }
         }
 
@@ -464,8 +470,6 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
 
     protected function storeEntityPhoneNumberPrimary(Entity $entity)
     {
-        $pdo = $this->getEntityManager()->getPDO();
-
         if (!$entity->has('phoneNumber')) return;
         $phoneNumberValue = trim($entity->get('phoneNumber'));
 
@@ -502,8 +506,10 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
                     $this->markNumberOptedOut($phoneNumberValue, !!$entity->get('phoneNumberIsOptedOut'));
                 }
 
-                $updateSelect = $this->getEntityManager()->createSelectBuilder()
+                $update = $this->getEntityManager()->getQueryBuilder()
+                    ->update()
                     ->from('EntityPhoneNumber')
+                    ->set( ['primary' => true])
                     ->where([
                         'entityId' => $entity->id,
                         'entityType' => $entity->getEntityType(),
@@ -511,7 +517,7 @@ class PhoneNumber extends \Espo\Core\Repositories\Database implements
                     ])
                     ->build();
 
-                $this->getEntityManager()->getQueryExecutor()->update($updateSelect, ['primary' => true]);
+                $this->getEntityManager()->getQueryExecutor()->run($update);
 
             } else {
                 if (
diff --git a/application/Espo/Repositories/Preferences.php b/application/Espo/Repositories/Preferences.php
index 3731876640..2c9db41c03 100644
--- a/application/Espo/Repositories/Preferences.php
+++ b/application/Espo/Repositories/Preferences.php
@@ -30,18 +30,14 @@
 namespace Espo\Repositories;
 
 use Espo\ORM\Entity;
-use Espo\ORM\Repository;
+use Espo\ORM\Repository\Repository;
 use Espo\Core\Utils\Json;
 
-use Espo\ORM\Repositories\{
-    Removable,
-};
-
 use PDO;
 
 use Espo\Core\Di;
 
-class Preferences extends Repository implements Removable,
+class Preferences extends Repository implements
     Di\MetadataAware,
     Di\ConfigAware,
     Di\EntityManagerAware
@@ -87,18 +83,17 @@ class Preferences extends Repository implements Removable,
     {
         $data = null;
 
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('Preferences', [
-            'select' => ['id', 'data'],
-            'whereClause' => [
+        $select = $this->getEntityManager()->getQueryBuilder()
+            ->select()
+            ->from('Preferences')
+            ->select(['id', 'data'])
+            ->where([
                 'id' => $id,
-            ],
-            'limit' => 1,
-        ]);
+            ])
+            ->limit(0, 1)
+            ->build();
 
-        $sth = $pdo->prepare($sql);
-        $sth->execute();
+        $sth = $this->getEntityManager()->getQueryExecutor()->run($select);
 
         while ($row = $sth->fetch(PDO::FETCH_ASSOC)) {
             $data = Json::decode($row['data']);
@@ -171,13 +166,15 @@ class Preferences extends Repository implements Removable,
 
         $entityTypeList = $entity->get('autoFollowEntityTypeList') ?? [];
 
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Autofollow', [
-            'whereClause' => [
+        $delete = $this->entityManager->getQueryBuilder()
+            ->delete()
+            ->from('Autofollow')
+            ->where([
                 'userId' => $id,
-            ],
-        ]);
+            ])
+            ->build();
 
-        $this->entityManager->getPDO()->query($sql);
+        $this->entityManager->getQueryExecutor()->run($delete);
 
         $entityTypeList = array_filter($entityTypeList, function ($item) {
             return (bool) $this->metadata->get(['scopes', $item, 'stream']);
@@ -208,20 +205,20 @@ class Preferences extends Repository implements Removable,
 
         $dataString = Json::encode($data, \JSON_PRETTY_PRINT);
 
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->entityManager->getQuery()->createInsertQuery('Preferences', [
-            'columns' => ['id', 'data'],
-            'values' => [
+        $insert = $this->getEntityManager()->getQueryBuilder()
+            ->insert()
+            ->into('Preferences')
+            ->columns(['id', 'data'])
+            ->values([
                 'id' => $entity->id,
                 'data' => $dataString,
-            ],
-            'update' => [
+            ])
+            ->updateSet([
                 'data' => $dataString,
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($insert);
 
         $user = $this->entityManager->getEntity('User', $entity->id);
         if ($user && !$user->isPortal()) {
@@ -233,15 +230,15 @@ class Preferences extends Repository implements Removable,
 
     public function deleteFromDb(string $id)
     {
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Preferences', [
-            'whereClause' => [
+        $delete = $this->getEntityManager()->getQueryBuilder()
+            ->delete()
+            ->from('Preferences')
+            ->where([
                 'id' => $id,
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->getEntityManager()->getQueryExecutor()->run($delete);
     }
 
     public function remove(Entity $entity, array $options = [])
diff --git a/application/Espo/Services/App.php b/application/Espo/Services/App.php
index 6efa7223d6..1c3b843283 100644
--- a/application/Espo/Services/App.php
+++ b/application/Espo/Services/App.php
@@ -334,7 +334,9 @@ class App
         $this->dataManager->rebuild();
     }
 
-    // TODO remove in 5.5.0
+    /**
+     * @todo Remove in 6.0.
+     */
     public function jobPopulatePhoneNumberNumeric()
     {
         $numberList = $this->entityManager->getRepository('PhoneNumber')->find();
@@ -343,7 +345,9 @@ class App
         }
     }
 
-    // TODO remove in 5.5.0
+    /**
+     * @todo Remove in 6.0. Move to another place. CLI command.
+     */
     public function jobPopulateArrayValues()
     {
         $scopeList = array_keys($this->metadata->get(['scopes']));
@@ -373,7 +377,7 @@ class App
                 $orGroup[$attribute . '!='] = null;
             }
 
-            $sql = $this->entityManager->getQuery()->createSelectQuery($scope, [
+            $sql = $this->entityManager->getQueryComposer()->createSelectQuery($scope, [
                 'select' => $select,
                 'whereClause' => [
                     'OR' => $orGroup
@@ -394,77 +398,9 @@ class App
         }
     }
 
-    // TODO remove in 5.5.0
-    public function jobPopulateNotesTeamUser()
-    {
-        $aclManager = $this->aclManager;
-
-        $sql = $this->entityManager->getQuery()->createSelectQuery('Note', [
-            'whereClause' => [
-                'parentId!=' => null,
-                'type=' => ['Relate', 'CreateRelated', 'EmailReceived', 'EmailSent', 'Assign', 'Create'],
-            ],
-            'limit' => 100000,
-            'orderBy' => [['number', 'DESC']]
-        ]);
-        $sth = $this->entityManager->getPdo()->prepare($sql);
-        $sth->execute();
-
-        $i = 0;
-        while ($dataRow = $sth->fetch(\PDO::FETCH_ASSOC)) {
-            $i++;
-            $note = $this->entityManager->getEntityFactory()->create('Note');
-            $note->set($dataRow);
-            $note->setAsFetched();
-
-            if ($note->get('relatedId') && $note->get('relatedType')) {
-                $targetType = $note->get('relatedType');
-                $targetId = $note->get('relatedId');
-            } else if ($note->get('parentId') && $note->get('parentType')) {
-                $targetType = $note->get('parentType');
-                $targetId = $note->get('parentId');
-            } else {
-                continue;
-            }
-
-            if (!$this->entityManager->hasRepository($targetType)) continue;
-
-            try {
-                $entity = $this->entityManager->getEntity($targetType, $targetId);
-                if (!$entity) continue;
-                $ownerUserIdAttribute = $aclManager->getImplementation($targetType)->getOwnerUserIdAttribute($entity);
-                $toSave = false;
-                if ($ownerUserIdAttribute) {
-                    if ($entity->getAttributeParam($ownerUserIdAttribute, 'isLinkMultipleIdList')) {
-                        $link = $entity->getAttributeParam($ownerUserIdAttribute, 'relation');
-                        $userIdList = $entity->getLinkMultipleIdList($link);
-                    } else {
-                        $userId = $entity->get($ownerUserIdAttribute);
-                        if ($userId) {
-                            $userIdList = [$userId];
-                        } else {
-                            $userIdList = [];
-                        }
-                    }
-                    if (!empty($userIdList)) {
-                        $note->set('usersIds', $userIdList);
-                        $toSave = true;
-                    }
-                }
-                if ($entity->hasLinkMultipleField('teams')) {
-                    $teamIdList = $entity->getLinkMultipleIdList('teams');
-                    if (!empty($teamIdList)) {
-                        $note->set('teamsIds', $teamIdList);
-                        $toSave = true;
-                    }
-                }
-                if ($toSave) {
-                    $this->entityManager->saveEntity($note);
-                }
-            } catch (\Exception $e) {}
-        }
-    }
-
+    /**
+     * @todo Remove in 6.0. Move to another place. CLI command.
+     */
     public function jobPopulateOptedOutPhoneNumbers()
     {
         $entityTypeList = ['Contact', 'Lead'];
diff --git a/application/Espo/Services/DashboardTemplate.php b/application/Espo/Services/DashboardTemplate.php
index 64d30daa58..5deb40bb66 100644
--- a/application/Espo/Services/DashboardTemplate.php
+++ b/application/Espo/Services/DashboardTemplate.php
@@ -109,7 +109,7 @@ class DashboardTemplate extends Record
         $team = $this->getEntityManager()->fetchEntity('Team', $teamId);
         if (!$team) throw new NotFound();
 
-        $userList = $this->getEntityManager()->getRepository('User')->join(['teams'])->distinct()->where([
+        $userList = $this->getEntityManager()->getRepository('User')->join('teams')->distinct()->where([
             'teams.id' => $teamId,
         ])->find();
 
diff --git a/application/Espo/Services/Email.php b/application/Espo/Services/Email.php
index 198754ce93..6c1d959196 100644
--- a/application/Espo/Services/Email.php
+++ b/application/Espo/Services/Email.php
@@ -522,8 +522,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['isRead' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -531,10 +532,11 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['isRead' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('Notification')
+            ->set(['read' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -544,7 +546,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['read' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
@@ -553,8 +555,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['isRead' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -562,7 +565,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['isRead' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         $this->markNotificationAsRead($id, $userId);
 
@@ -573,8 +576,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['isRead' => false])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -582,7 +586,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['isRead' => false]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
@@ -591,8 +595,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['isImportant' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -600,7 +605,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['isImportant' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
@@ -609,8 +614,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['isImportant' => false])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -618,7 +624,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['isImportant' => false]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
@@ -627,8 +633,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['inTrash' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -636,7 +643,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['inTrash' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         $this->markNotificationAsRead($id, $userId);
 
@@ -647,8 +654,9 @@ class Email extends Record implements
     {
         $userId = $userId ?? $this->getUser()->id;
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['inTrash' => false])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -656,15 +664,16 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['inTrash' => false]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
 
     public function markNotificationAsRead(string $id, string $userId)
     {
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('Notification')
+            ->set(['read' => true])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -675,7 +684,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['read' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
     }
 
     public function moveToFolder(string $id, ?string $folderId, ?string $userId = null)
@@ -686,8 +695,9 @@ class Email extends Record implements
             $folderId = null;
         }
 
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('EmailUser')
+            ->set(['folderId' => $folderId])
             ->where([
                 'deleted' => false,
                 'userId' => $userId,
@@ -695,7 +705,7 @@ class Email extends Record implements
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['folderId' => $folderId]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
diff --git a/application/Espo/Services/EmailAddress.php b/application/Espo/Services/EmailAddress.php
index 1fbc5564f4..6697cfe23a 100644
--- a/application/Espo/Services/EmailAddress.php
+++ b/application/Espo/Services/EmailAddress.php
@@ -144,26 +144,20 @@ class EmailAddress extends Record
             return [];
         }
 
-        $pdo = $this->getEntityManager()->getPDO();
+        $list = $this->getEntityManager()->getRepository('InboundEmail')
+            ->select(['id', 'name', 'emailAddress'])
+            ->where([
+                'emailAddress*' => $query . '%',
+            ])
+            ->order('name')
+            ->find();
 
-        $selectParams = [
-            'select' => ['id', 'name', 'emailAddress'],
-            'whereClause' => [
-                'emailAddress*' => $query . '%'
-            ],
-            'orderBy' => 'name',
-        ];
-
-        $sql = $this->getEntityManager()->getQuery()->createSelectQuery('InboundEmail', $selectParams);
-
-        $sth = $pdo->prepare($sql);
-        $sth->execute();
-        while ($row = $sth->fetch(\PDO::FETCH_ASSOC)) {
+        foreach ($list as $item) {
             $result[] = [
-                'emailAddress' => $row['emailAddress'],
-                'entityName' => $row['name'],
+                'emailAddress' => $item->get('emailAddress'),
+                'entityName' => $item->get('name'),
                 'entityType' => 'InboundEmail',
-                'entityId' => $row['id'],
+                'entityId' => $item->get('id'),
             ];
         }
     }
diff --git a/application/Espo/Services/EmailNotification.php b/application/Espo/Services/EmailNotification.php
index 69271b51c8..3f076b5a75 100644
--- a/application/Espo/Services/EmailNotification.php
+++ b/application/Espo/Services/EmailNotification.php
@@ -222,14 +222,14 @@ class EmailNotification
             $selectParams = $this->$methodName();
             $selectParams['whereClause'][] = $where;
 
-            $sqlArr[] = $this->entityManager->getQuery()->createSelectQuery('Notification', $selectParams);
+            $sqlArr[] = $this->entityManager->getQueryComposer()->createSelectQuery('Notification', $selectParams);
         }
 
         $maxCount = intval(self::PROCESS_MAX_COUNT);
 
         $sql = '' . implode(' UNION ', $sqlArr) . " ORDER BY number LIMIT 0, {$maxCount}";
 
-        $notificationList = $this->entityManager->getRepository('Notification')->findByQuery($sql);
+        $notificationList = $this->entityManager->getRepository('Notification')->findBySql($sql);
 
         foreach ($notificationList as $notification) {
             $notification->set('emailIsProcessed', true);
diff --git a/application/Espo/Services/GlobalSearch.php b/application/Espo/Services/GlobalSearch.php
index 5ecf8ffa6e..678be0e5dd 100644
--- a/application/Espo/Services/GlobalSearch.php
+++ b/application/Espo/Services/GlobalSearch.php
@@ -98,7 +98,7 @@ class GlobalSearch implements
                 $selectParams['orderBy'] = [['name']];
             }
 
-            $itemSql = $this->entityManager->getQuery()->createSelectQuery($entityType, $selectParams);
+            $itemSql = $this->entityManager->getQueryComposer()->createSelectQuery($entityType, $selectParams);
 
             $unionPartList[] = "(\n" . $itemSql . "\n)";
         }
@@ -127,7 +127,7 @@ class GlobalSearch implements
             $sql .= "\nORDER BY name";
         }
 
-        $sql = $this->entityManager->getQuery()->limit($sql, $offset, $maxSize + 1);
+        $sql = $this->entityManager->getQueryComposer()->limit($sql, $offset, $maxSize + 1);
 
         $sth = $pdo->prepare($sql);
         $sth->execute();
diff --git a/application/Espo/Services/InboundEmail.php b/application/Espo/Services/InboundEmail.php
index 7ae9240a4c..58616ad5dd 100644
--- a/application/Espo/Services/InboundEmail.php
+++ b/application/Espo/Services/InboundEmail.php
@@ -643,14 +643,15 @@ class InboundEmail extends \Espo\Services\Record implements
             $case->set('accountId', $email->get('accountId'));
         }
 
-        $contact = $this->getEntityManager()->getRepository('Contact')->join([['emailAddresses', 'emailAddressesMultiple']])->where([
+        $contact = $this->getEntityManager()->getRepository('Contact')->join('emailAddresses', 'emailAddressesMultiple')->where([
             'emailAddressesMultiple.id' => $email->get('fromEmailAddressId')
         ])->findOne();
         if ($contact) {
             $case->set('contactId', $contact->id);
         } else {
             if (!$case->get('accountId')) {
-                $lead = $this->getEntityManager()->getRepository('Lead')->join([['emailAddresses', 'emailAddressesMultiple']])->where([
+                $lead = $this->getEntityManager()->getRepository('Lead')
+                ->join('emailAddresses', 'emailAddressesMultiple')->where([
                     'emailAddressesMultiple.id' => $email->get('fromEmailAddressId')
                 ])->findOne();
                 if ($lead) {
diff --git a/application/Espo/Services/Notification.php b/application/Espo/Services/Notification.php
index 95085d07bf..58561a8888 100644
--- a/application/Espo/Services/Notification.php
+++ b/application/Espo/Services/Notification.php
@@ -80,7 +80,6 @@ class Notification extends \Espo\Services\Record implements
 
         $collection = $this->entityManager->createCollection();
 
-
         $userList = $this->getEntityManager()->getRepository('User')
             ->select(['id'])
             ->where([
@@ -176,15 +175,16 @@ class Notification extends \Espo\Services\Record implements
 
     public function markAllRead(string $userId)
     {
-        $select = $this->entityManager->createSelectBuilder()
+        $update = $this->entityManager->getQueryBuilder()->update()
             ->from('Notification')
+            ->set(['read' => true])
             ->where([
                 'userId' => $userId,
                 'read' => false,
             ])
             ->build();
 
-        $this->entityManager->getQueryExecutor()->update($select, ['read' => true]);
+        $this->entityManager->getQueryExecutor()->run($update);
 
         return true;
     }
@@ -276,13 +276,15 @@ class Notification extends \Espo\Services\Record implements
         }
 
         if (!empty($ids)) {
-            $select = $this->entityManager->createSelectBuilder()
+            $update = $this->entityManager->getQueryBuilder()
+                ->update()
                 ->from('Notification')
+                ->set(['read' => true])
                 ->where([
                     'id' => $ids,
                 ])
                 ->build();
-            $this->entityManager->getQueryExecutor()->update($select, ['read' => true]);
+            $this->entityManager->getQueryExecutor()->run($update);
         }
 
         return new RecordCollection($collection, $count);
diff --git a/application/Espo/Services/Record.php b/application/Espo/Services/Record.php
index 1d492c9ffa..f12ae0b002 100644
--- a/application/Espo/Services/Record.php
+++ b/application/Espo/Services/Record.php
@@ -385,22 +385,28 @@ class Record implements Crud,
 
     public function getEntity(?string $id = null) : ?Entity
     {
-        if (!is_null($id)) {
-            $selectParams = [];
-            if ($this->getUser()->isAdmin()) {
-                $selectParams['withDeleted'] = true;
-            }
-            $entity = $this->getRepository()->getById($id, $selectParams);
-        } else {
-            $entity = $this->getRepository()->getNew();
+        if ($id === null) {
+            return $this->getRepository()->getNew();
         }
 
-        if ($entity && !is_null($id)) {
-            $this->loadAdditionalFields($entity);
-            if (!$this->getAcl()->check($entity, 'read')) throw new ForbiddenSilent("No read access.");
-            $this->prepareEntityForOutput($entity);
+        $entity = $this->getRepository()->getById($id);
+
+        if (!$entity && $this->getUser()->isAdmin()) {
+            $entity = $this->getEntityEvenDeleted($id);
         }
 
+        if (!$entity) {
+            return null;
+        }
+
+        $this->loadAdditionalFields($entity);
+
+        if (!$this->getAcl()->check($entity, 'read')) {
+            throw new ForbiddenSilent("No read access.");
+        }
+
+        $this->prepareEntityForOutput($entity);
+
         return $entity;
     }
 
@@ -1325,11 +1331,25 @@ class Record implements Crud,
         ];
     }
 
+    protected function getEntityEvenDeleted(string $id) : ?Entity
+    {
+        $query = $this->entityManager->getQueryBuilder()
+            ->select()
+            ->from($this->entityType)
+            ->where([
+                'id' => $id,
+            ])
+            ->withDeleted()
+            ->build();
+
+        return $this->getRepository()->findOne($query);
+    }
+
     public function restoreDeleted(string $id)
     {
         if (!$this->getUser()->isAdmin()) throw new Forbidden();
 
-        $entity = $this->getRepository()->getById($id, ['withDeleted' => true]);
+        $entity = $this->getEntityEvenDeleted($id);
 
         if (!$entity) throw new NotFound();
         if (!$entity->get('deleted')) throw new Forbidden();
@@ -2095,7 +2115,10 @@ class Record implements Crud,
 
             $this->getEntityManager()->getRepository($this->getEntityType())->handleSelectParams($selectParams);
 
-            $collection = $this->getEntityManager()->createSthCollection($this->getEntityType(), $selectParams);
+            $collection = $this->getEntityManager()->getCollectionFactroy()->createFromQuery(
+                $this->getEntityType(),
+                SelectQuery::fromRaw($selectParams)
+            );
         }
 
         $attributeListToSkip = [
diff --git a/application/Espo/Services/Stream.php b/application/Espo/Services/Stream.php
index 24d8af952f..2913934be4 100644
--- a/application/Espo/Services/Stream.php
+++ b/application/Espo/Services/Stream.php
@@ -35,6 +35,7 @@ use Espo\Core\Exceptions\NotFound;
 use Espo\ORM\{
     Entity,
     EntityCollection,
+    QueryParams\Select,
 };
 use Espo\Entities\User;
 
@@ -240,17 +241,17 @@ class Stream
             return;
         }
 
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Subscription', [
-            'whereClause' => [
+        $delete = $this->entityManager->getQueryBuilder()
+            ->delete()
+            ->from('Subscription')
+            ->where([
                 'userId' => $userIdList,
                 'entityId' => $entity->id,
                 'entityType' => $entity->getEntityType(),
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->entityManager->getQueryExecutor()->run($delete);
 
         $collection = new EntityCollection();
 
@@ -264,7 +265,7 @@ class Stream
             $collection[] = $subscription;
         }
 
-        $this->entityManager->getMapper('RDB')->massInsert($collection);
+        $this->entityManager->getMapper()->massInsert($collection);
     }
 
     public function followEntity(Entity $entity, string $userId, bool $skipAclCheck = false)
@@ -309,17 +310,17 @@ class Stream
             return false;
         }
 
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Subscription', [
-            'whereClause' => [
+        $delete = $this->entityManager->getQueryBuilder()
+            ->delete()
+            ->from('Subscription')
+            ->where([
                 'userId' => $userId,
                 'entityId' => $entity->id,
                 'entityType' => $entity->getEntityType(),
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->entityManager->getQueryExecutor()->run($delete);
 
         return true;
     }
@@ -330,16 +331,16 @@ class Stream
             return;
         }
 
-        $pdo = $this->entityManager->getPDO();
-
-        $sql = $this->entityManager->getQuery()->createDeleteQuery('Subscription', [
-            'whereClause' => [
+        $delete = $this->entityManager->getQueryBuilder()
+            ->delete()
+            ->from('Subscription')
+            ->where([
                 'entityId' => $entity->id,
                 'entityType' => $entity->getEntityType(),
-            ],
-        ]);
+            ])
+            ->build();
 
-        $pdo->query($sql);
+        $this->entityManager->getQueryExecutor()->run($delete);
     }
 
     public function findUserStream($userId, $params = [])
@@ -633,11 +634,7 @@ class Stream
 
         if ($user->isPortal()) {
             $portalIdList = $user->getLinkMultipleIdList('portals');
-            $portalIdQuotedList = [];
-            foreach ($portalIdList as $portalId) {
-                $portalIdQuotedList[] = $pdo->quote($portalId);
-            }
-            if (!empty($portalIdQuotedList)) {
+            if (!empty($portalIdList)) {
                 $selectParamsList[] = [
                     'select' => $select,
                     'leftJoins' => ['portals', 'createdBy'],
@@ -730,16 +727,18 @@ class Stream
                 }
             }
 
-            $sqlPartList[] = "(\n" . $this->entityManager->getQuery()->createSelectQuery('Note', $selectParams) . "\n)";
+            $sqlPartList[] = "(\n" . $this->entityManager->getQueryComposer()->createSelectQuery('Note', $selectParams) . "\n)";
         }
 
         $sql = implode("\n UNION ALL \n", $sqlPartList) . "
             ORDER BY number DESC
         ";
 
-        $sql = $this->entityManager->getQuery()->limit($sql, $offset, $maxSize + 1);
+        $sql = $this->entityManager->getQueryComposer()->limit($sql, $offset, $maxSize + 1);
 
-        $collection = $this->entityManager->getRepository('Note')->findByQuery($sql);
+        $sthCollection = $this->entityManager->getRepository('Note')->findBySql($sql);
+
+        $collection = $this->entityManager->getCollectionFactory()->createFromSthCollection($sthCollection);
 
         foreach ($collection as $e) {
             $this->loadNoteAdditionalFields($e);
@@ -1090,9 +1089,15 @@ class Stream
 
         $selectManager->applyLimit($offset, $maxSize + 1, $selectParams);
 
-        $sql = $this->entityManager->getQuery()->createSelectQuery('Note', $selectParams);
+        $selectParams['from'] = 'Note';
 
-        $collection = $this->entityManager->getRepository('Note')->findByQuery($sql);
+        $select = Select::fromRaw($selectParams);
+
+        $sql = $this->entityManager->getQueryComposer()->compose($select);
+
+        $sthCollection = $this->entityManager->getRepository('Note')->findBySql($sql);
+
+        $collection = $this->entityManager->getCollectionFactory()->createFromSthCollection($sthCollection);
 
         foreach ($collection as $e) {
             $this->loadNoteAdditionalFields($e);
@@ -1611,9 +1616,8 @@ class Stream
             $selectParams['select'] = $selectAttributeList;
         }
 
-        $query = $this->entityManager->getQuery();
+        $query = $this->entityManager->getQueryComposer();
         $selectParams['t'] = true;
-        $sql = $query->createSelectQuery('User', $selectParams);
 
         $collection = $this->entityManager->getRepository('User')->find($selectParams);
         $total = $this->entityManager->getRepository('User')->count($selectParams);
@@ -1623,49 +1627,41 @@ class Stream
 
     public function getEntityFollowers(Entity $entity, $offset = 0, $limit = false)
     {
-        $query = $this->entityManager->getQuery();
-        $pdo = $this->entityManager->getPDO();
-
         if (!$limit) {
             $limit = 200;
         }
 
-        $sql = $query->createSelectQuery('User', [
-            'select' => ['id', 'name'],
-            'joins' => [
+        $userList = $this->entityManager->getRepository('User')
+            ->select(['id', 'name'])
+            ->join(
+                'Subscription',
+                'subscription',
                 [
-                    'Subscription',
-                    'subscription',
-                    [
-                        'subscription.userId=:' => 'user.id',
-                        'subscription.entityId' => $entity->id,
-                        'subscription.entityType' => $entity->getEntityType()
-                    ]
+                    'subscription.userId=:' => 'user.id',
+                    'subscription.entityId' => $entity->id,
+                    'subscription.entityType' => $entity->getEntityType()
                 ]
-            ],
-            'offset' => $offset,
-            'limit' => $limit,
-            'whereClause' => [
-                'isActive' => true
-            ],
-            'orderBy' => [
+            )
+            ->limit($offset, $limit)
+            ->where([
+                'isActive' => true,
+            ])
+            ->order([
                 ['LIST:id:' . $this->user->id, 'DESC'],
-                ['name']
-            ]
-        ]);
-
-        $sth = $pdo->prepare($sql);
-        $sth->execute();
+                ['name'],
+            ])
+            ->find();
 
         $data = [
             'idList' => [],
             'nameMap' => (object) []
         ];
 
-        while ($row = $sth->fetch(\PDO::FETCH_ASSOC)) {
-            $id = $row['id'];
+        foreach ($userList as $user) {
+            $id = $user->id;
+
             $data['idList'][] = $id;
-            $data['nameMap']->$id = $row['name'];
+            $data['nameMap']->$id = $user->get('name');
         }
 
         return $data;
diff --git a/tests/unit/Espo/ORM/EntityTest.php b/tests/unit/Espo/ORM/EntityTest.php
index 417e3415be..005238036d 100644
--- a/tests/unit/Espo/ORM/EntityTest.php
+++ b/tests/unit/Espo/ORM/EntityTest.php
@@ -27,9 +27,11 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-use Espo\ORM\DB\MysqlMapper;
-use Espo\ORM\DB\Query\Mysql as Query;
-use Espo\ORM\EntityFactory;
+use Espo\ORM\{
+    DB\MysqlMapper,
+    DB\Query\Mysql as Query,
+    EntityFactory,
+};
 
 use Espo\Entities\Job;
 
diff --git a/tests/unit/Espo/ORM/DB/MapperTest.php b/tests/unit/Espo/ORM/MapperTest.php
similarity index 85%
rename from tests/unit/Espo/ORM/DB/MapperTest.php
rename to tests/unit/Espo/ORM/MapperTest.php
index 00fecfcd0e..dc970e0952 100644
--- a/tests/unit/Espo/ORM/DB/MapperTest.php
+++ b/tests/unit/Espo/ORM/MapperTest.php
@@ -27,19 +27,26 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-use Espo\ORM\DB\MysqlMapper;
-use Espo\ORM\DB\Query\MysqlQuery as Query;
-use Espo\ORM\EntityFactory;
-use Espo\ORM\EntityCollection;
+use Espo\ORM\{
+    Metadata,
+    EntityManager,
+    EntityFactory,
+    CollectionFactory,
+    EntityCollection,
+    QueryComposer\MysqlQueryComposer as QueryComposer,
+    Mapper\MysqlMapper,
+    QueryParams\Select,
+};
 
-use Espo\Entities\Post;
-use Espo\Entities\Comment;
-use Espo\Entities\Tag;
-use Espo\Entities\Note;
-use Espo\Entities\Job;
+use Espo\Entities\{
+    Post,
+    Comment,
+    Tag,
+    Note,
+    Job,
+};
 
 require_once 'tests/unit/testData/DB/Entities.php';
-require_once 'tests/unit/testData/DB/MockPDO.php';
 require_once 'tests/unit/testData/DB/MockDBResult.php';
 
 class DBMapperTest extends \PHPUnit\Framework\TestCase
@@ -53,7 +60,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
 
     protected function setUp() : void
     {
-        $this->pdo = $this->createMock('MockPDO');
+        $this->pdo = $this->getMockBuilder(PDO::class)->disableOriginalConstructor()->getMock();
         $this->pdo
                 ->expects($this->any())
                 ->method('quote')
@@ -62,33 +69,49 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
                     return "'" . $args[0] . "'";
                 }));
 
-        $metadata = $this->getMockBuilder('Espo\\ORM\\Metadata')->disableOriginalConstructor()->getMock();
+        $metadata = $this->getMockBuilder(Metadata::class)->disableOriginalConstructor()->getMock();
         $metadata
             ->method('get')
             ->will($this->returnValue(false));
 
-        $entityManager = $this->getMockBuilder('Espo\\ORM\\EntityManager')->disableOriginalConstructor()->getMock();
+        $entityManager = $this->getMockBuilder(EntityManager::class)->disableOriginalConstructor()->getMock();
         $entityManager
             ->method('getMetadata')
             ->will($this->returnValue($metadata));
 
-        $this->entityFactory = $this->getMockBuilder('Espo\\ORM\\EntityFactory')->disableOriginalConstructor()->getMock();
+        $this->entityFactory = $this->getMockBuilder(EntityFactory::class)->disableOriginalConstructor()->getMock();
         $this->entityFactory
             ->expects($this->any())
             ->method('create')
-            ->will($this->returnCallback(function () use ($entityManager) {
-                $args = func_get_args();
-                $className = "\\Espo\\Entities\\" . $args[0];
-                return new $className($args[0], [], $entityManager);
-            }));
+            ->will($this->returnCallback(
+                function () use ($entityManager) {
+                    $args = func_get_args();
+                    $className = "Espo\\Entities\\" . $args[0];
+                    return new $className($args[0], [], $entityManager);
+                }
+            ));
+
+        $entityFactory = $this->entityFactory;
+
+        $this->collectionFactory = $this->getMockBuilder(CollectionFactory::class)->disableOriginalConstructor()->getMock();
+        $this->collectionFactory
+            ->expects($this->any())
+            ->method('create')
+            ->will($this->returnCallback(
+                function () use ($entityFactory) {
+                    $args = func_get_args();
+                    $entityType = $args[0] ?? null;
+                    $dataList = $args[1] ?? [];
+
+                    return new EntityCollection($dataList, $entityType, $entityFactory);
+                }
+            ));
 
         $this->metadata = $this->getMockBuilder('Espo\\ORM\\Metadata')->disableOriginalConstructor()->getMock();
 
-        $this->query = new Query($this->pdo, $this->entityFactory, $this->metadata);
+        $this->query = new QueryComposer($this->pdo, $this->entityFactory, $this->metadata);
 
-        $this->db = new MysqlMapper($this->pdo, $this->entityFactory, $this->query, $this->metadata);
-
-        $entityFactory = $this->entityFactory;
+        $this->db = new MysqlMapper($this->pdo, $this->entityFactory, $this->collectionFactory, $this->query, $this->metadata);
 
         $this->post = $entityFactory->create('Post');
         $this->comment = $entityFactory->create('Comment');
@@ -120,30 +143,43 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
                   ->will($this->returnValue($return));
     }
 
-    public function testSelectById()
+    public function testSelectOne()
     {
         $query =
-            "SELECT post.id AS `id`, post.name AS `name`, NULLIF(TRIM(CONCAT(IFNULL(createdBy.salutation_name, ''), IFNULL(createdBy.first_name, ''), ' ', IFNULL(createdBy.last_name, ''))), '') AS `createdByName`, post.created_by_id AS `createdById`, post.deleted AS `deleted` ".
+            "SELECT post.id AS `id`, post.name AS `name`, NULLIF(TRIM(CONCAT(IFNULL(createdBy.salutation_name, ''), " .
+            "IFNULL(createdBy.first_name, ''), ' ', IFNULL(createdBy.last_name, ''))), '') AS `createdByName`, ".
+             "post.created_by_id AS `createdById`, post.deleted AS `deleted` ".
             "FROM `post` ".
             "LEFT JOIN `user` AS `createdBy` ON post.created_by_id = createdBy.id " .
             "WHERE post.id = '1' AND post.deleted = 0";
-        $return = new MockDBResult(array(
-            array(
+
+        $return = new MockDBResult([
+            [
                 'id' => '1',
                 'name' => 'test',
                 'deleted' => false,
-            ),
-        ));
+            ],
+        ]);
         $this->mockQuery($query, $return);
 
-        $this->db->selectById($this->post, '1');
-        $this->assertEquals($this->post->id, '1');
+        $select = Select::fromRaw([
+            'from' => 'Post',
+            'whereClause' => [
+                'id' => '1',
+            ],
+        ]);
+
+        $post = $this->db->selectOne($select);
+
+        $this->assertEquals($post->id, '1');
     }
 
     public function testSelect1()
     {
         $query =
-            "SELECT post.id AS `id`, post.name AS `name`, NULLIF(TRIM(CONCAT(IFNULL(createdBy.salutation_name, ''), IFNULL(createdBy.first_name, ''), ' ', IFNULL(createdBy.last_name, ''))), '') AS `createdByName`, post.created_by_id AS `createdById`, post.deleted AS `deleted` ".
+            "SELECT post.id AS `id`, post.name AS `name`, NULLIF(TRIM(CONCAT(IFNULL(createdBy.salutation_name, ''), " .
+            "IFNULL(createdBy.first_name, ''), ' ', IFNULL(createdBy.last_name, ''))), '') AS `createdByName`, " .
+            "post.created_by_id AS `createdById`, post.deleted AS `deleted` ".
             "FROM `post` ".
             "LEFT JOIN `user` AS `createdBy` ON post.created_by_id = createdBy.id " .
             "JOIN `post_tag` AS `tagsMiddle` ON post.id = tagsMiddle.post_id AND tagsMiddle.deleted = 0 ".
@@ -152,39 +188,41 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "WHERE post.name = 'test_1' AND (post.id = '100' OR post.name LIKE 'test_%') AND tags.name = 'yoTag' AND post.deleted = 0 ".
             "ORDER BY post.name DESC ".
             "LIMIT 0, 10";
-        $return = new MockDBResult(array(
-            array(
+
+        $return = new MockDBResult([
+            [
                 'id' => '2',
                 'name' => 'test_2',
                 'deleted' => false,
-            ),
-            array(
+            ],
+            [
                 'id' => '1',
                 'name' => 'test_1',
                 'deleted' => false,
-            ),
-        ));
+            ],
+        ]);
         $this->mockQuery($query, $return);
 
-        $selectParams = array(
-            'whereClause' => array(
+        $selectParams = [
+            'from' => 'Post',
+            'whereClause' => [
                 'name' => 'test_1',
-                'OR' => array(
+                'OR' => [
                     'id' => '100',
                     'name*' => 'test_%',
-                ),
+                ],
                 'tags.name' => 'yoTag',
-            ),
+            ],
             'order' => 'DESC',
             'orderBy' => 'name',
             'limit' => 10,
-            'joins' => array(
+            'joins' => [
                 'tags',
                 'comments',
-            ),
-        );
-        $list = $this->db->select($this->post, $selectParams);
+            ],
+        ];
 
+        $list = $this->db->select(Select::fromRaw($selectParams));
 
         $this->assertTrue($list[0] instanceof Post);
         $this->assertTrue(isset($list[0]->id));
@@ -194,51 +232,65 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
     public function testSelectWithSpecifiedParams()
     {
         $query =
-            "SELECT contact.id AS `id`, TRIM(CONCAT(contact.first_name, ' ', contact.last_name)) AS `name`, contact.first_name AS `firstName`, contact.last_name AS `lastName`, contact.deleted AS `deleted` ".
+            "SELECT contact.id AS `id`, TRIM(CONCAT(contact.first_name, ' ', contact.last_name)) AS `name`, " .
+            "contact.first_name AS `firstName`, contact.last_name AS `lastName`, contact.deleted AS `deleted` ".
             "FROM `contact` ".
-            "WHERE (contact.first_name LIKE 'test%' OR contact.last_name LIKE 'test%' OR CONCAT(contact.first_name, ' ', contact.last_name) LIKE 'test%') AND contact.deleted = 0 ".
+            "WHERE " .
+            "(contact.first_name LIKE 'test%' OR contact.last_name LIKE 'test%' OR CONCAT(contact.first_name, ' ', contact.last_name) " .
+                "LIKE 'test%') ".
+            "AND contact.deleted = 0 ".
             "ORDER BY contact.first_name DESC, contact.last_name DESC ".
             "LIMIT 0, 10";
 
-        $return = new MockDBResult(array(
-            array(
+        $return = new MockDBResult([
+            [
                 'id' => '1',
                 'name' => 'test',
                 'deleted' => false,
-            ),
-        ));
+            ],
+        ]);
+
         $this->mockQuery($query, $return);
 
-        $selectParams = array(
-            'whereClause' => array(
+        $selectParams = [
+            'from' => 'Contact',
+            'whereClause' => [
                 'name*' => 'test%',
-            ),
+            ],
             'order' => 'DESC',
             'orderBy' => 'name',
-            'limit' => 10
-        );
-        $list = $this->db->select($this->contact, $selectParams);
+            'limit' => 10,
+        ];
+
+        $list = $this->db->select(Select::fromRaw($selectParams));
     }
 
     public function testJoin()
     {
         $query =
-            "SELECT comment.id AS `id`, comment.post_id AS `postId`, post.name AS `postName`, comment.name AS `name`, comment.deleted AS `deleted` ".
+            "SELECT comment.id AS `id`, comment.post_id AS `postId`, post.name AS `postName`, comment.name AS `name`, " .
+            "comment.deleted AS `deleted` ".
             "FROM `comment` ".
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id ".
             "WHERE comment.deleted = 0";
-        $return = new MockDBResult(array(
-            array(
+
+        $return = new MockDBResult([
+            [
                 'id' => '11',
                 'postId' => '1',
                 'postName' => 'test',
                 'name' => 'test_comment',
                 'deleted' => false,
-            ),
-        ));
+            ],
+        ]);
+
         $this->mockQuery($query, $return);
 
-        $list = $this->db->select($this->comment);
+        $selectParams = [
+            'from' => 'Comment',
+        ];
+
+        $list = $this->db->select(Select::fromRaw($selectParams));
 
         $this->assertTrue($list[0] instanceof Comment);
         $this->assertTrue($list[0]->has('postName'));
@@ -252,6 +304,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "FROM `tag` ".
             "JOIN `post_tag` AS `postTag` ON postTag.tag_id = tag.id AND postTag.post_id = '1' AND postTag.deleted = 0 ".
             "WHERE tag.deleted = 0";
+
         $return = new MockDBResult([
             [
                 'id' => '1',
@@ -259,8 +312,10 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
                 'deleted' => false,
             ],
         ]);
+
         $this->mockQuery($query, $return);
         $this->post->id = '1';
+
         $list = $this->db->selectRelated($this->post, 'tags');
 
         $this->assertTrue($list[0] instanceof Tag);
@@ -284,11 +339,15 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, $return);
         $this->account->id = '1';
 
-        $list = $this->db->selectRelated($this->account, 'teams', [
-            'additionalColumns' => [
-                'teamId' => 'stub',
+        $select = Select::fromRaw([
+            'from' => 'Team',
+            'select' => [
+                '*',
+                ['entityTeam.teamId', 'stub'],
             ],
         ]);
+
+        $list = $this->db->selectRelated($this->account, 'teams', $select);
     }
 
     public function testSelectRelatedHasChildren()
@@ -298,13 +357,15 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "note.id AS `id`, note.name AS `name`, note.parent_id AS `parentId`, note.parent_type AS `parentType`, note.deleted AS `deleted` ".
             "FROM `note` ".
             "WHERE note.parent_id = '1' AND note.parent_type = 'Post' AND note.deleted = 0";
-        $return = new MockDBResult(array(
-            array(
+
+        $return = new MockDBResult([
+            [
                 'id' => '1',
                 'name' => 'test',
                 'deleted' => false,
-            ),
-        ));
+            ],
+        ]);
+
         $this->mockQuery($query, $return);
         $this->post->id = '1';
         $list = $this->db->selectRelated($this->post, 'notes');
@@ -343,7 +404,6 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($post->get('name'), 'test');
     }
 
-
     public function testCountRelated()
     {
         $query =
@@ -351,14 +411,17 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "FROM `tag` ".
             "JOIN `post_tag` AS `postTag` ON postTag.tag_id = tag.id AND postTag.post_id = '1' AND postTag.deleted = 0 ".
             "WHERE tag.deleted = 0";
+
         $return = new MockDBResult([
             [
                 'value' => 1,
             ],
         ]);
+
         $this->mockQuery($query, $return);
 
         $this->post->id = '1';
+
         $count = $this->db->countRelated($this->post, 'tags');
 
         $this->assertEquals($count, 1);
@@ -368,6 +431,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
     {
         $query = "INSERT INTO `post` (`id`, `name`) VALUES ('1', 'test')";
         $return = true;
+
         $this->mockQuery($query, $return);
 
         $this->post->reset();
@@ -509,6 +573,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
 
         $this->note->id = 'noteId';
         $this->post->id = 'postId';
+
         $this->db->unrelate($this->note, 'parent', $this->post);
     }
 
@@ -533,6 +598,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, true);
 
         $this->post->id = 'postId';
+
         $this->db->unrelateById($this->post, 'comments', 'commentId');
     }
 
@@ -545,6 +611,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, true);
 
         $this->post->id = 'postId';
+
         $this->db->unrelateAll($this->post, 'comments');
     }
 
@@ -571,6 +638,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, true);
 
         $this->post->id = 'postId';
+
         $this->db->unrelateById($this->post, 'notes', 'noteId');
     }
 
@@ -583,6 +651,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, true);
 
         $this->post->id = 'postId';
+
         $this->db->unrelateAll($this->post, 'notes');
     }
 
@@ -593,6 +662,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, $return);
 
         $this->post->id = '1';
+
         $this->db->unrelateById($this->post, 'tags', '100');
     }
 
@@ -603,6 +673,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->mockQuery($query, $return);
 
         $this->post->id = '1';
+
         $this->db->unrelateAll($this->post, 'tags');
     }
 
@@ -611,10 +682,11 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $query =
             "UPDATE `entity_team` SET entity_team.deleted = 1 ".
             "WHERE entity_team.entity_id = '1' AND entity_team.team_id = '100' AND entity_team.entity_type = 'Account'";
-        $return = true;
-        $this->mockQuery($query, $return);
+
+        $this->mockQuery($query, true);
 
         $this->account->id = '1';
+
         $this->db->unrelateById($this->account, 'teams', '100');
     }
 
@@ -624,8 +696,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "UPDATE `entity_team` SET entity_team.deleted = 1 ".
             "WHERE entity_team.entity_id = '1' AND entity_team.entity_type = 'Account'";
 
-        $return = true;
-        $this->mockQuery($query, $return);
+        $this->mockQuery($query, true);
 
         $this->account->id = '1';
         $this->db->unrelateAll($this->account, 'teams');
@@ -634,8 +705,8 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
     public function testUnrelateManyToMany()
     {
         $query = "UPDATE `post_tag` SET post_tag.deleted = 1 WHERE post_tag.post_id = 'postId' AND post_tag.tag_id = 'tagId'";
-        $return = true;
-        $this->mockQuery($query, $return);
+
+        $this->mockQuery($query, true);
 
         $this->post->id = 'postId';
         $this->tag->id = 'tagId';
@@ -802,7 +873,8 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
             "WHERE post_tag.post_id = 'postId' AND post_tag.tag_id = 'tagId'";
 
         $query3 =
-            "UPDATE `post_tag` SET post_tag.deleted = 0, post_tag.role = 'Test' WHERE post_tag.post_id = 'postId' AND post_tag.tag_id = 'tagId'";
+            "UPDATE `post_tag` SET post_tag.deleted = 0, post_tag.role = 'Test' " .
+            "WHERE post_tag.post_id = 'postId' AND post_tag.tag_id = 'tagId'";
 
         $ps = $this->createMock(\PDOStatement::class);
         $ps->expects($this->exactly(1))
@@ -896,7 +968,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals('test', $result);
     }
 
-    public function testUpdateRelation()
+    public function testUpdateRelationColumns()
     {
         $this->post->id = 'postId';
         $this->tag->id = 'tagId';
@@ -907,7 +979,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
 
         $this->mockQuery($query);
 
-        $this->db->updateRelation($this->post, 'tags', 'tagId', [
+        $this->db->updateRelationColumns($this->post, 'tags', 'tagId', [
             'role' => 'test'
         ]);
     }
@@ -922,7 +994,7 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
         ]);
         $this->mockQuery($query, $return);
 
-        $value = $this->db->max($this->post, array(), 'id', true);
+        $value = $this->db->max(Select::fromRaw(['from' => 'Post']), 'id');
 
         $this->assertEquals($value, 10);
     }
@@ -938,11 +1010,14 @@ class DBMapperTest extends \PHPUnit\Framework\TestCase
 
         $this->post->id = '1';
 
-        $this->db->massRelate($this->post, 'tags', [
+        $select = Select::fromRaw([
+            'from' => 'Tag',
             'whereClause' => [
                 'name' => 'test',
             ],
         ]);
+
+        $this->db->massRelate($this->post, 'tags', $select);
     }
 
     public function testDeleteFromDb1()
diff --git a/tests/unit/Espo/ORM/MetadataTest.php b/tests/unit/Espo/ORM/MetadataTest.php
new file mode 100644
index 0000000000..2c8a374ae0
--- /dev/null
+++ b/tests/unit/Espo/ORM/MetadataTest.php
@@ -0,0 +1,99 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+use Espo\ORM\{
+    Metadata,
+};
+
+class MetadataTest extends \PHPUnit\Framework\TestCase
+{
+    protected function setUp() : void
+    {
+
+    }
+
+    public function testHas1()
+    {
+        $metadata = new Metadata([
+            'Test' => [],
+        ]);
+
+        $this->assertTrue($metadata->has('Test'));
+    }
+
+    public function testHas2()
+    {
+        $metadata = new Metadata([
+            'Test' => [],
+        ]);
+
+        $this->assertFalse($metadata->has('Hello'));
+    }
+
+    public function testGet1()
+    {
+        $metadata = new Metadata([
+            'Test' => [
+                'indexes' => [],
+            ],
+        ]);
+
+        $this->assertEquals([], $metadata->get('Test', 'indexes'));
+    }
+
+    public function testGet2()
+    {
+        $metadata = new Metadata([
+            'Test' => [
+                'relations' => [
+                    'test' => [
+                        'type' => 'hasMany',
+                    ],
+                ],
+            ],
+        ]);
+
+        $this->assertEquals('hasMany', $metadata->get('Test', 'relations.test.type'));
+    }
+
+    public function testGet3()
+    {
+        $metadata = new Metadata([
+            'Test' => [
+                'relations' => [
+                    'test' => [
+                        'type' => 'hasMany',
+                    ],
+                ],
+            ],
+        ]);
+
+        $this->assertEquals('hasMany', $metadata->get('Test', ['relations', 'test', 'type']));
+    }
+}
diff --git a/tests/unit/Espo/ORM/DB/QueryTest.php b/tests/unit/Espo/ORM/MysqlQueryComposerTest.php
similarity index 79%
rename from tests/unit/Espo/ORM/DB/QueryTest.php
rename to tests/unit/Espo/ORM/MysqlQueryComposerTest.php
index a2992dcea8..4d522ffeca 100644
--- a/tests/unit/Espo/ORM/DB/QueryTest.php
+++ b/tests/unit/Espo/ORM/MysqlQueryComposerTest.php
@@ -27,22 +27,35 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-use Espo\ORM\DB\Query\MysqlQuery as Query;
-use Espo\ORM\EntityFactory;
-use Espo\ORM\Metadata;
 
-use Espo\Core\ORM\EntityManager;
+use Espo\ORM\{
+    EntityFactory,
+    Metadata,
+    QueryComposer\MysqlQueryComposer as QueryComposer,
+    QueryBuilder,
+    EntityManager,
+};
 
-use Espo\Entities\Post;
-use Espo\Entities\Comment;
-use Espo\Entities\Tag;
-use Espo\Entities\Note;
+use Espo\ORM\QueryParams\{
+    Select,
+    Insert,
+    Update,
+    Delete,
+};
+
+
+use Espo\Entities\{
+    Post,
+    Comment,
+    Tag,
+    Note,
+};
 
 require_once 'tests/unit/testData/DB/Entities.php';
 require_once 'tests/unit/testData/DB/MockPDO.php';
 require_once 'tests/unit/testData/DB/MockDBResult.php';
 
-class QueryTest extends \PHPUnit\Framework\TestCase
+class MysqlQueryComposerTest extends \PHPUnit\Framework\TestCase
 {
     protected $query;
 
@@ -52,6 +65,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     protected function setUp() : void
     {
+        $this->queryBuilder = new QueryBuilder();
+
         $this->pdo = $this->createMock('MockPDO');
         $this->pdo
                 ->expects($this->any())
@@ -80,7 +95,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
         $this->getMockBuilder('Espo\\ORM\\Metadata')->disableOriginalConstructor()->getMock();
 
-        $this->query = new Query($this->pdo, $this->entityFactory, $this->metadata);
+        $this->query = new QueryComposer($this->pdo, $this->entityFactory, $this->metadata);
 
         $entityFactory = $this->entityFactory;
 
@@ -106,11 +121,12 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testDelete1()
     {
-        $sql = $this->query->createDeleteQuery('Account', [
+        $sql = $this->query->compose(Delete::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "DELETE FROM `account` " .
@@ -121,13 +137,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testDeleteWithLimit()
     {
-        $sql = $this->query->createDeleteQuery('Account', [
+        $sql = $this->query->compose(Delete::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
             ],
             'orderBy' => 'name',
             'limit' => 1,
-        ]);
+        ]));
 
         $expectedSql =
             "DELETE FROM `account` " .
@@ -140,12 +157,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testDeleteWithDeleted()
     {
-        $sql = $this->query->createDeleteQuery('Account', [
+        $sql = $this->query->compose(Delete::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
                 'deleted' => true,
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "DELETE FROM `account` " .
@@ -156,15 +174,16 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testUpdateQuery1()
     {
-        $sql = $this->query->createUpdateQuery('Account', [
+        $sql = $this->query->compose(Update::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
             ],
-            'update' => [
+            'set' => [
                 'deleted' => false,
                 'name' => 'hello',
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "UPDATE `account` " .
@@ -176,15 +195,16 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testUpdateQueryWithJoin()
     {
-        $sql = $this->query->createUpdateQuery('Comment', [
+        $sql = $this->query->compose(Update::fromRaw([
+            'from' => 'Comment',
             'whereClause' => [
                 'name' => 'test',
             ],
             'joins' => ['post'],
-            'update' => [
+            'set' => [
                 'name:' => 'post.name',
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "UPDATE `comment` " .
@@ -197,16 +217,17 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testUpdateQueryWithOrder()
     {
-        $sql = $this->query->createUpdateQuery('Account', [
+        $sql = $this->query->compose(Update::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
             ],
             'orderBy' => 'name',
-            'update' => [
+            'set' => [
                 'deleted' => false,
                 'name' => 'hello',
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "UPDATE `account` " .
@@ -219,17 +240,18 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testUpdateQueryWithLimit()
     {
-        $sql = $this->query->createUpdateQuery('Account', [
+        $sql = $this->query->compose(Update::fromRaw([
+            'from' => 'Account',
             'whereClause' => [
                 'name' => 'test',
             ],
             'orderBy' => 'name',
             'limit' => 1,
-            'update' => [
+            'set' => [
                 'deleted' => false,
                 'name' => 'hello',
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "UPDATE `account` " .
@@ -243,13 +265,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testInsertQuery1()
     {
-        $sql = $this->query->createInsertQuery('Account', [
+        $sql = $this->query->compose(Insert::fromRaw([
+            'into' => 'Account',
             'columns' => ['id', 'name'],
             'values' => [
                 'id' => '1',
                 'name' => 'hello',
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "INSERT INTO `account` (`id`, `name`) VALUES ('1', 'hello')";
@@ -259,7 +282,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testInsertQuery2()
     {
-        $sql = $this->query->createInsertQuery('Account', [
+        $sql = $this->query->compose(Insert::fromRaw([
+            'into' => 'Account',
             'columns' => ['id', 'name'],
             'values' => [
                 [
@@ -271,7 +295,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                     'name' => 'test',
                 ],
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "INSERT INTO `account` (`id`, `name`) VALUES ('1', 'hello'), ('2', 'test')";
@@ -281,17 +305,18 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testInsertUpdate()
     {
-        $sql = $this->query->createInsertQuery('Account', [
+        $sql = $this->query->compose(Insert::fromRaw([
+            'into' => 'Account',
             'columns' => ['id', 'name'],
             'values' => [
                 'id' => '1',
                 'name' => 'hello',
             ],
-            'update' => [
+            'updateSet' => [
                 'deleted' => false,
                 'name' => 'test'
             ],
-        ]);
+        ]));
 
         $expectedSql =
             "INSERT INTO `account` (`id`, `name`) VALUES ('1', 'hello') ON DUPLICATE KEY UPDATE `deleted` = 0, `name` = 'test'";
@@ -299,14 +324,19 @@ class QueryTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
     }
 
-    public function testSelectAllColumns()
+    public function testSelectAllColumns1()
     {
-        $sql = $this->query->createSelectQuery('Account', [
-            'orderBy' => 'name',
-            'order' => 'ASC',
-            'offset' => 10,
-            'limit' => 20
-        ]);
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Account')
+            ->order('name', 'ASC')
+            ->where([
+                'deleted' => false,
+            ])
+            ->limit(10, 20)
+            ->build();
+
+        $sql = $this->query->compose($select);
 
         $expectedSql =
             "SELECT account.id AS `id`, account.name AS `name`, account.deleted AS `deleted` FROM `account` " .
@@ -315,15 +345,59 @@ class QueryTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
     }
 
+    public function testSelectAllColumns2()
+    {
+        $expectedSql =
+            "SELECT account.id AS `id`, account.name AS `name`, account.deleted AS `deleted` FROM `account` " .
+            "WHERE account.deleted = 0";
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Account')
+            ->select(['*'])
+            ->where([
+                'deleted' => false,
+            ])
+            ->build();
+
+        $sql = $this->query->compose($select);
+
+        $this->assertEquals($expectedSql, $sql);
+    }
+
+    public function testSelectAllColumnsWithExtra()
+    {
+        $expectedSql =
+            "SELECT account.id AS `id`, account.name AS `name`, account.deleted AS `deleted`, LOWER(account.name) AS `lowerName` " .
+            "FROM `account` " .
+            "WHERE account.deleted = 0";
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Account')
+            ->select(['*', ['LOWER:name', 'lowerName']])
+            ->where([
+                'deleted' => false,
+            ])
+            ->build();
+
+        $sql = $this->query->compose($select);
+
+        $this->assertEquals($expectedSql, $sql);
+    }
+
     public function testSelectSkipTextColumns()
     {
-        $sql = $this->query->createSelectQuery('Article', [
-            'orderBy' => 'name',
-            'order' => 'ASC',
-            'offset' => 10,
-            'limit' => 20,
-            'skipTextColumns' => true
-        ]);
+        $sql = $this->query->compose(
+            Select::fromRaw([
+                'from' => 'Article',
+                'orderBy' => 'name',
+                'order' => 'ASC',
+                'offset' => 10,
+                'limit' => 20,
+                'skipTextColumns' => true,
+            ])
+        );
 
         $expectedSql =
             "SELECT article.id AS `id`, article.name AS `name`, article.deleted AS `deleted` FROM `article` " .
@@ -334,8 +408,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testSelectWithBelongsToJoin()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
-        ]);
+        $sql = $this->query->compose(
+            Select::fromRaw([
+                'from' => 'Comment',
+            ])
+        );
 
         $expectedSql =
             "SELECT comment.id AS `id`, comment.post_id AS `postId`, post.name AS `postName`, comment.name AS `name`, comment.deleted AS `deleted` FROM `comment` " .
@@ -347,18 +424,24 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testSelectWithSpecifiedColumns()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
-            'select' => ['id', 'name']
-        ]);
+        $sql = $this->query->compose(
+            Select::fromRaw([
+                'from' => 'Comment',
+                'select' => ['id', 'name']
+            ])
+        );
+
         $expectedSql =
             "SELECT comment.id AS `id`, comment.name AS `name` FROM `comment` " .
             "WHERE comment.deleted = 0";
 
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
-            'select' => array('id', 'name', 'postName')
-        ));
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
+            'select' => ['id', 'name', 'postName'],
+        ]));
+
         $expectedSql =
             "SELECT comment.id AS `id`, comment.name AS `name`, post.name AS `postName` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -366,10 +449,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('id', 'name', 'postName'),
-            'leftJoins' => array('post')
-        ));
+            'leftJoins' => array('post'),
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, comment.name AS `name`, post.name AS `postName` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -377,10 +461,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('id', 'name'),
             'leftJoins' => array('post')
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, comment.name AS `name` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -391,20 +476,22 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testSelectUseIndex()
     {
-        $sql = $this->query->createSelectQuery('Account', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Account',
             'select' => ['id', 'name'],
             'useIndex' => 'name',
-        ]);
+        ]));
         $expectedSql =
             "SELECT account.id AS `id`, account.name AS `name` FROM `account` USE INDEX (`IDX_NAME`) " .
             "WHERE account.deleted = 0";
 
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Account', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Account',
             'select' => ['id', 'name'],
             'useIndex' => ['name'],
-        ]);
+        ]));
         $expectedSql =
             "SELECT account.id AS `id`, account.name AS `name` FROM `account` USE INDEX (`IDX_NAME`) " .
             "WHERE account.deleted = 0";
@@ -414,11 +501,12 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testWithSpecifiedFunction()
     {
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('id', 'postId', 'post.name', 'COUNT:id'),
             'leftJoins' => array('post'),
             'groupBy' => array('postId', 'post.name')
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, comment.post_id AS `postId`, post.name AS `post.name`, COUNT(comment.id) AS `COUNT:id` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -427,11 +515,12 @@ class QueryTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
 
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('id', 'COUNT:id', 'MONTH:post.createdAt'),
             'leftJoins' => array('post'),
             'groupBy' => array('MONTH:post.createdAt')
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, COUNT(comment.id) AS `COUNT:id`, DATE_FORMAT(post.created_at, '%Y-%m') AS `MONTH:post.createdAt` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -442,10 +531,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testSelectWithJoinChildren()
     {
-        $sql = $this->query->createSelectQuery('Post', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'leftJoins' => [['notes', 'notesLeft']]
-        ));
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -457,10 +547,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinConditions1()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'leftJoins' => [['notes', 'notesLeft', ['notesLeft.name!=' => null]]]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -473,10 +564,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinConditions2()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'leftJoins' => [['notes', 'notesLeft', ['notesLeft.name=:' => 'post.name']]]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -489,7 +581,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinConditions3()
     {
-        $sql = $this->query->createSelectQuery('Note', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Note',
             'select' => ['id'],
             'leftJoins' => [['post', 'post', [
                 'OR' => [
@@ -498,7 +591,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                 ]
             ]]],
             'withDeleted' => true,
-        ]);
+        ]));
 
         $expectedSql = "SELECT note.id AS `id` FROM `note` LEFT JOIN `post` AS `post` ON (post.name = 'test' OR post.name IS NULL)";
 
@@ -507,7 +600,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinConditions4()
     {
-        $sql = $this->query->createSelectQuery('Note', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Note',
             'select' => ['id'],
             'leftJoins' => [['post', 'post', [
                 'name' => null,
@@ -517,7 +611,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                 ]
             ]]],
             'withDeleted' => true,
-        ]);
+        ]));
 
         $expectedSql = "SELECT note.id AS `id` FROM `note` LEFT JOIN `post` AS `post` ON post.name IS NULL AND (post.name = 'test' OR post.name IS NULL)";
 
@@ -526,10 +620,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinTable()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'leftJoins' => [['NoteTable', 'note', ['note.parentId=:' => 'post.id', 'note.parentType' => 'Post']]]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -542,10 +637,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testJoinOnlyMiddle()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id'],
             'leftJoins' => [['tags', null, null, ['onlyMiddle' => true]]]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id` FROM `post` " .
@@ -557,12 +653,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testWhereNotValue1()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'name!=:' => 'post.id'
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -573,13 +670,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testWhereNotValue2()
     {
-        $sql = $this->query->createSelectQuery('Post', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'name:' => null
             ],
             'withDeleted' => true
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT post.id AS `id`, post.name AS `name` FROM `post` " .
@@ -590,7 +688,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testSelectWithSubquery()
     {
-        $sql = $this->query->createSelectQuery('Post', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'whereClause' => array(
                 'post.id=s' => array(
@@ -603,12 +702,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                     )
                 )
             )
-        ));
+        ]));
 
         $expectedSql = "SELECT post.id AS `id`, post.name AS `name` FROM `post` WHERE post.id IN (SELECT post.id AS `id` FROM `post` WHERE post.name = 'test' AND post.deleted = 0) AND post.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Post', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'whereClause' => array(
                 'post.id!=s' => array(
@@ -621,13 +721,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                     )
                 )
             )
-        ));
+        ]));
 
         $expectedSql = "SELECT post.id AS `id`, post.name AS `name` FROM `post` WHERE post.id NOT IN (SELECT post.id AS `id` FROM `post` WHERE post.name = 'test' AND post.deleted = 0) AND post.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
 
 
-        $sql = $this->query->createSelectQuery('Post', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Post',
             'select' => ['id', 'name'],
             'whereClause' => array(
                 'NOT'=> array(
@@ -635,7 +736,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                     'post.createdById' => '1'
                 )
             )
-        ));
+        ]));
 
         $expectedSql = "SELECT post.id AS `id`, post.name AS `name` FROM `post` WHERE post.id NOT IN (SELECT post.id AS `id` FROM `post` WHERE post.name = 'test' AND post.created_by_id = '1' AND post.deleted = 0) AND post.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
@@ -643,10 +744,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testGroupBy()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['COUNT:id', 'QUARTER:comment.createdAt'],
             'groupBy' => ['QUARTER:comment.createdAt']
-        ]);
+        ]));
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, CONCAT(YEAR(comment.created_at), '_', QUARTER(comment.created_at)) AS `QUARTER:comment.createdAt` FROM `comment` " .
             "WHERE comment.deleted = 0 " .
@@ -654,10 +756,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
 
 
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['COUNT:id', 'YEAR_5:comment.createdAt'],
             'groupBy' => ['YEAR_5:comment.createdAt']
-        ]);
+        ]));
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, CASE WHEN MONTH(comment.created_at) >= 6 THEN YEAR(comment.created_at) ELSE YEAR(comment.created_at) - 1 END AS `YEAR_5:comment.createdAt` FROM `comment` " .
             "WHERE comment.deleted = 0 " .
@@ -665,10 +768,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
 
 
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['COUNT:id', 'QUARTER_4:comment.createdAt'],
             'groupBy' => ['QUARTER_4:comment.createdAt']
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, CASE WHEN MONTH(comment.created_at) >= 5 THEN CONCAT(YEAR(comment.created_at), '_', FLOOR((MONTH(comment.created_at) - 5) / 3) + 1) ELSE CONCAT(YEAR(comment.created_at) - 1, '_', CEIL((MONTH(comment.created_at) + 7) / 3)) END AS `QUARTER_4:comment.createdAt` FROM `comment` " .
@@ -679,12 +783,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testOrderBy()
     {
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('COUNT:id', 'YEAR:post.createdAt'),
             'leftJoins' => array('post'),
             'groupBy' => array('YEAR:post.createdAt'),
             'orderBy' => 2
-        ));
+        ]));
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, YEAR(post.created_at) AS `YEAR:post.createdAt` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -693,12 +798,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
             "ORDER BY 2 ASC";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('COUNT:id', 'post.name'),
             'leftJoins' => array('post'),
             'groupBy' => array('post.name'),
             'orderBy' => 'LIST:post.name:Test,Hello',
-        ));
+        ]));
 
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, post.name AS `post.name` FROM `comment` " .
@@ -708,7 +814,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
             "ORDER BY FIELD(post.name, 'Hello', 'Test') DESC";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('COUNT:id', 'YEAR:post.createdAt', 'post.name'),
             'leftJoins' => array('post'),
             'groupBy' => array('YEAR:post.createdAt', 'post.name'),
@@ -716,7 +823,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
                 array(2, 'DESC'),
                 array('LIST:post.name:Test,Hello')
             )
-        ));
+        ]));
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:id`, YEAR(post.created_at) AS `YEAR:post.createdAt`, post.name AS `post.name` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -728,14 +835,15 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testForeign()
     {
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => array('COUNT:comment.id', 'postId', 'postName'),
             'leftJoins' => array('post'),
             'groupBy' => array('postId'),
             'whereClause' => array(
                 'post.createdById' => 'id_1'
             ),
-        ));
+        ]));
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:comment.id`, comment.post_id AS `postId`, post.name AS `postName` FROM `comment` " .
             "LEFT JOIN `post` AS `post` ON comment.post_id = post.id " .
@@ -746,46 +854,50 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testInArray()
     {
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => array(
                 'id' => ['id_1']
             ),
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE comment.id IN ('id_1') AND comment.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => array(
                 'id!=' => ['id_1']
             ),
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE comment.id NOT IN ('id_1') AND comment.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => array(
                 'id' => []
             ),
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE 0 AND comment.deleted = 0";
         $this->assertEquals($expectedSql, $sql);
 
-        $sql = $this->query->createSelectQuery('Comment', array(
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => array(
                 'name' => 'Test',
                 'id!=' => []
             ),
-        ));
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE comment.name = 'Test' AND 1 AND comment.deleted = 0";
@@ -794,12 +906,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction1()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => [
                 'MONTH_NUMBER:comment.created_at' => 2
             ]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE MONTH(comment.created_at) = '2' AND comment.deleted = 0";
@@ -808,12 +921,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction2()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => [
                 'WEEK_NUMBER_1:createdAt' => 2
             ]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE WEEK(comment.created_at, 3) = '2' AND comment.deleted = 0";
@@ -822,12 +936,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction3()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => [
                 'MONTH_NUMBER:(comment.created_at)' => 2
             ]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE MONTH(comment.created_at) = '2' AND comment.deleted = 0";
@@ -836,12 +951,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction4()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => [
                 "CONCAT:(MONTH:comment.created_at,' ',CONCAT:(comment.name,'+'))" => 'Test Hello'
             ]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id` FROM `comment` " .
             "WHERE CONCAT(DATE_FORMAT(comment.created_at, '%Y-%m'), ' ', CONCAT(comment.name, '+')) = 'Test Hello' AND comment.deleted = 0";
@@ -850,11 +966,12 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction5()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', ['FLOOR:3.5', 'FLOOR:3.5']],
             'whereClause' => [
             ]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, FLOOR('3.5') AS `FLOOR:3.5` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -863,10 +980,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction6()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', ['ROUND:3.5,1', 'ROUND:3.5,1']],
             'whereClause' => []
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, ROUND('3.5', '1') AS `ROUND:3.5,1` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -875,10 +993,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction7()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', 'ROUND:3.5,1'],
             'whereClause' => []
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, ROUND('3.5', '1') AS `ROUND:3.5,1` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -887,9 +1006,10 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction8()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', ["CONCAT:(',test',\"+\",'\"', \"'\")", 'value']]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, CONCAT(',test', '+', '\"', ''') AS `value` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -898,9 +1018,10 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction9()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', ["COALESCE:(name,FALSE,true,null)", 'value']]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, COALESCE(comment.name, FALSE, TRUE, NULL) AS `value` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -909,9 +1030,10 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction10()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', ["IF:(LIKE:(name,'%test%'),'1','0')", 'value']]
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, IF(comment.name LIKE '%test%', '1', '0') AS `value` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -920,10 +1042,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction11()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => [["IS_NULL:(name)", 'value1'], ["IS_NOT_NULL:(name)", 'value2']],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.name IS NULL AS `value1`, comment.name IS NOT NULL AS `value2` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -931,10 +1054,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction12()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ["IF:(OR:('1','0'),'1',' ')"],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT IF('1' OR '0', '1', ' ') AS `IF:(OR:('1','0'),'1',' ')` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -942,10 +1066,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction13()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ["IN:(name,'1','0')"],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.name IN ('1', '0') AS `IN:(name,'1','0')` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -953,10 +1078,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction14()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ["NOT:(name)"],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT NOT comment.name AS `NOT:(name)` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -964,10 +1090,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction15()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ["MUL:(2,2.5,SUB:(3,1))"],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT ('2' * '2.5' * ('3' - '1')) AS `MUL:(2,2.5,SUB:(3,1))` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -975,10 +1102,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction16()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ["NOW:()"],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT NOW() AS `NOW:()` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -986,10 +1114,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction17()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => [["TIMESTAMPDIFF_YEAR:('2016-10-10', '2018-10-10')", 'test']],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT TIMESTAMPDIFF(YEAR, '2016-10-10', '2018-10-10') AS `test` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -997,10 +1126,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunction18()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => [["IFNULL:(name, '')", 'test']],
             'withDeleted' => true
-        ]);
+        ]));
         $expectedSql =
             "SELECT IFNULL(comment.name, '') AS `test` FROM `comment`";
         $this->assertEquals($expectedSql, $sql);
@@ -1008,10 +1138,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunctionTZ1()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', "MONTH_NUMBER:TZ:(comment.created_at,-3.5)"],
             'whereClause' => []
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, MONTH(CONVERT_TZ(comment.created_at, '+00:00', '-03:30')) AS `MONTH_NUMBER:TZ:(comment.created_at,-3.5)` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -1020,10 +1151,11 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testFunctionTZ2()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id', "MONTH_NUMBER:TZ:(comment.created_at,0)"],
             'whereClause' => []
-        ]);
+        ]));
         $expectedSql =
             "SELECT comment.id AS `id`, MONTH(CONVERT_TZ(comment.created_at, '+00:00', '+00:00')) AS `MONTH_NUMBER:TZ:(comment.created_at,0)` FROM `comment` " .
             "WHERE comment.deleted = 0";
@@ -1032,7 +1164,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testHaving()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['COUNT:comment.id', 'postId', 'postName'],
             'leftJoins' => ['post'],
             'groupBy' => ['postId'],
@@ -1042,7 +1175,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
             'havingClause' => [
                 'COUNT:comment.id>' => 1
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT COUNT(comment.id) AS `COUNT:comment.id`, comment.post_id AS `postId`, post.name AS `postName` " .
@@ -1055,13 +1188,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testWhere1()
     {
-        $sql = $this->query->createSelectQuery('Comment', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Comment',
             'select' => ['id'],
             'whereClause' => [
                 'post.createdById<=' => '1'
             ],
             'withDeleted' => true
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT comment.id AS `id` " .
@@ -1072,13 +1206,14 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch1()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'MATCH_BOOLEAN:name,description:test +hello',
                 'id!=' => null
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, article.name AS `name` FROM `article` " .
@@ -1089,12 +1224,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch2()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'MATCH_NATURAL_LANGUAGE:description:"test hello"'
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, article.name AS `name` FROM `article` " .
@@ -1105,7 +1241,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch3()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', 'MATCH_BOOLEAN:description:test'],
             'whereClause' => [
                 'MATCH_BOOLEAN:description:test'
@@ -1113,7 +1250,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
             'orderBy' => [
                 [2, 'DESC']
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, MATCH (article.description) AGAINST ('test' IN BOOLEAN MODE) AS `MATCH_BOOLEAN:description:test` FROM `article` " .
@@ -1125,7 +1262,8 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch4()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', ['MATCH_BOOLEAN:description:test', 'relevance']],
             'whereClause' => [
                 'MATCH_BOOLEAN:description:test'
@@ -1133,7 +1271,7 @@ class QueryTest extends \PHPUnit\Framework\TestCase
             'orderBy' => [
                 [2, 'DESC']
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, MATCH (article.description) AGAINST ('test' IN BOOLEAN MODE) AS `relevance` FROM `article` " .
@@ -1145,12 +1283,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch5()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'MATCH_NATURAL_LANGUAGE:description:test>' => 1
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, article.name AS `name` FROM `article` " .
@@ -1161,12 +1300,13 @@ class QueryTest extends \PHPUnit\Framework\TestCase
 
     public function testMatch6()
     {
-        $sql = $this->query->createSelectQuery('Article', [
+        $sql = $this->query->compose(Select::fromRaw([
+            'from' => 'Article',
             'select' => ['id', 'name'],
             'whereClause' => [
                 'MATCH_NATURAL_LANGUAGE:(description,test)'
             ]
-        ]);
+        ]));
 
         $expectedSql =
             "SELECT article.id AS `id`, article.name AS `name` FROM `article` " .
diff --git a/tests/unit/Espo/ORM/QueryBuilderTest.php b/tests/unit/Espo/ORM/QueryBuilderTest.php
new file mode 100644
index 0000000000..7f415e922b
--- /dev/null
+++ b/tests/unit/Espo/ORM/QueryBuilderTest.php
@@ -0,0 +1,126 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+use Espo\ORM\{
+    QueryBuilder,
+    QueryParams\Select,
+    QueryParams\Insert,
+    QueryParams\Update,
+    QueryParams\Delete,
+};
+
+class QueryBuilderTest extends \PHPUnit\Framework\TestCase
+{
+    protected function setUp() : void
+    {
+        $this->queryBuilder = new QueryBuilder();
+    }
+
+    public function testClone1()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->build();
+
+        $clonedSelect = $this->queryBuilder
+            ->clone($select)
+            ->distinct()
+            ->build();
+
+        $this->assertNotSame($clonedSelect, $select);
+        $this->assertInstanceOf(Select::class, $clonedSelect);
+    }
+
+    public function testInsert1()
+    {
+        $insert = $this->queryBuilder
+            ->insert()
+            ->into('Test')
+            ->columns(['col1'])
+            ->values(['col1' => '1'])
+            ->build();
+
+        $this->assertInstanceOf(Insert::class, $insert);
+    }
+
+    public function testInsert2()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->build();
+
+        $insert = $this->queryBuilder
+            ->insert()
+            ->into('Test')
+            ->columns(['col1'])
+            ->valuesQuery($select)
+            ->build();
+
+        $this->assertInstanceOf(Insert::class, $insert);
+    }
+
+    public function testDelete1()
+    {
+        $delete = $this->queryBuilder
+            ->delete()
+            ->from('Test')
+            ->where(['col1' => '1'])
+            ->limit(1)
+            ->build();
+
+        $this->assertInstanceOf(Delete::class, $delete);
+    }
+
+    public function testUpdate1()
+    {
+        $update = $this->queryBuilder
+            ->update()
+            ->from('Test')
+            ->set(['col1' => '2'])
+            ->where(['col1' => '1'])
+            ->limit(1)
+            ->build();
+
+        $this->assertInstanceOf(Update::class, $update);
+    }
+
+    public function testUpdateNoSet()
+    {
+        $this->expectException(\RuntimeException::class);
+
+        $update = $this->queryBuilder
+            ->update()
+            ->from('Test')
+            ->where(['col1' => '1'])
+            ->limit(1)
+            ->build();
+    }
+}
diff --git a/tests/unit/Espo/ORM/QueryParams/SelectBuilderTest.php b/tests/unit/Espo/ORM/QueryParams/SelectBuilderTest.php
new file mode 100644
index 0000000000..5c13531f9f
--- /dev/null
+++ b/tests/unit/Espo/ORM/QueryParams/SelectBuilderTest.php
@@ -0,0 +1,241 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2020 Yuri Kuznetsov, Taras Machyshyn, Oleksiy Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace tests\unit\Espo\ORM\QueryParams;
+
+use Espo\ORM\{
+    EntityManager,
+    QueryParams\Select,
+    QueryParams\SelectBuilder,
+};
+
+class SelectBuilderTest extends \PHPUnit\Framework\TestCase
+{
+    protected function setUp() : void
+    {
+        $this->builder = new SelectBuilder();
+    }
+
+    public function testFrom()
+    {
+        $params = $this->builder
+            ->from('Test')
+            ->build()
+            ->getRawParams();
+
+        $this->assertEquals('Test', $params['from']);
+    }
+
+    public function testSelect1()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->select(['id', 'name'])
+            ->select('test')
+            ->build();
+
+        $this->assertEquals(['id', 'name', 'test'], $select->getSelect());
+    }
+
+    public function testSelect2()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->select('test')
+            ->select(['id', 'name'])
+            ->build();
+
+        $this->assertEquals(['id', 'name'], $select->getSelect());
+    }
+
+    public function testSelect3()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->select('test', 'hello')
+            ->build();
+
+        $this->assertEquals([['test', 'hello']], $select->getSelect());
+    }
+
+    public function testCloneNotSame()
+    {
+        $builder = new SelectBuilder();
+
+        $select = $builder
+            ->from('Test')
+            ->build();
+
+        $builder = new SelectBuilder();
+
+        $selectCloned = $builder
+            ->clone($select)
+            ->build();
+
+        $this->assertNotSame($selectCloned, $select);
+    }
+
+    public function testWhereNull1()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->where(['test' => null])
+            ->build();
+
+        $raw = $select->getRawParams();
+
+        $this->assertEquals(['test' => null], $raw['whereClause']);
+    }
+
+    public function testWhereNull2()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->where('test', null)
+            ->build();
+
+        $raw = $select->getRawParams();
+
+        $this->assertEquals(['test' => null], $raw['whereClause']);
+    }
+
+    public function testGroupBy()
+    {
+        $select = $this->builder
+            ->from('Test')
+            ->having(['test' => null])
+            ->groupBy(['test'])
+            ->build();
+
+        $raw = $select->getRawParams();
+
+        $this->assertEquals(['test' => null], $raw['havingClause']);
+
+        $this->assertEquals(['test'], $raw['groupBy']);
+    }
+
+    public function testClone()
+    {
+        $builder = new SelectBuilder();
+
+        $select = $builder
+            ->from('Test')
+            ->where('test1', '1')
+            ->build();
+
+        $builder = new SelectBuilder();
+
+        $selectCloned = $builder
+            ->clone($select)
+            ->distinct()
+            ->where('test2', '2')
+            ->build();
+
+        $params = $select->getRawParams();
+        $paramsCloned = $selectCloned->getRawParams();
+
+        $this->assertTrue($paramsCloned['distinct']);
+        $this->assertFalse($params['distinct'] ?? false);
+
+        $this->assertEquals(['test1' =>'1'], $params['whereClause']);
+        $this->assertEquals(['test1' => '1', 'test2' => '2'], $paramsCloned['whereClause']);
+    }
+
+    public function testCloneException()
+    {
+        $builder = new SelectBuilder();
+
+        $select = $builder
+            ->from('Test')
+            ->where('test1', '1')
+            ->build();
+
+        $builder = new SelectBuilder();
+
+        $this->expectException(\RuntimeException::class);
+
+        $builder
+            ->from('Test')
+            ->clone($select);
+    }
+
+    public function testWhereSameKeys1()
+    {
+        $builder = new SelectBuilder();
+
+        $select = $builder
+            ->from('Test')
+            ->where(['test' => '1'])
+            ->where(['test' => '2'])
+            ->build();
+
+        $raw = $select->getRawParams();
+
+        $expected = [
+            'test' => '1',
+            ['test' => '2'],
+        ];
+
+        $this->assertEquals($expected, $raw['whereClause']);
+    }
+
+    public function testWhereSameKeys2()
+    {
+        $builder = new SelectBuilder();
+
+        $select = $builder
+            ->from('Test')
+            ->where([
+                'OR' => [
+                    'test' => '1'
+                ],
+            ])
+            ->where([
+                'OR' => [
+                    'test' => '2'
+                ],
+            ])
+            ->build();
+
+        $raw = $select->getRawParams();
+
+        $expected = [
+            'OR' => [
+                'test' => '1'
+            ],
+            [
+                'OR' => [
+                    'test' => '2'
+                ],
+            ]
+        ];
+
+        $this->assertEquals($expected, $raw['whereClause']);
+    }
+}
diff --git a/tests/unit/Espo/ORM/RDBRepositoryTest.php b/tests/unit/Espo/ORM/RDBRepositoryTest.php
index 9a29903969..3c01474ae8 100644
--- a/tests/unit/Espo/ORM/RDBRepositoryTest.php
+++ b/tests/unit/Espo/ORM/RDBRepositoryTest.php
@@ -30,25 +30,34 @@
 require_once 'tests/unit/testData/DB/Entities.php';
 
 use Espo\ORM\{
-    DB\MysqlMapper,
-    DB\Query\Mysql as Query,
-    Repositories\RDB as Repository,
+    Mapper\MysqlMapper,
+    Repository\RDBRepository as Repository,
+    Repository\RDBRelation,
+    Repository\RDBRelationSelectBuilder,
     EntityCollection,
-};
-
-use Espo\Core\ORM\{
+    QueryParams\Select,
+    QueryBuilder,
+    Entity,
     EntityManager,
     EntityFactory,
+    CollectionFactory,
 };
 
 use tests\unit\testData\Entities\Test;
 
+use Espo\Entities;
+
 class RDBRepositoryTest extends \PHPUnit\Framework\TestCase
 {
     protected function setUp() : void
     {
-        $entityManager = $this->entityManager = $this->getMockBuilder(EntityManager::class)->disableOriginalConstructor()->getMock();
-        $entityFactory = $this->getMockBuilder(EntityFactory::class)->disableOriginalConstructor()->getMock();
+        $entityManager = $this->entityManager =
+            $this->getMockBuilder(EntityManager::class)->disableOriginalConstructor()->getMock();
+
+        $entityFactory = $this->entityFactory =
+        $this->getMockBuilder(EntityFactory::class)->disableOriginalConstructor()->getMock();
+
+        $this->collectionFactory = new CollectionFactory($this->entityManager);
 
         $this->mapper = $this->getMockBuilder(MysqlMapper::class)->disableOriginalConstructor()->getMock();
 
@@ -56,19 +65,56 @@ class RDBRepositoryTest extends \PHPUnit\Framework\TestCase
             ->method('getMapper')
             ->will($this->returnValue($this->mapper));
 
+        $this->queryBuilder = new QueryBuilder();
+
+        $entityManager
+            ->method('getQueryBuilder')
+            ->will($this->returnValue($this->queryBuilder));
+
+        $entityManager
+            ->method('getQueryBuilder')
+            ->will($this->returnValue($this->queryBuilder));
+
+        $entityManager
+            ->method('getCollectionFactory')
+            ->will($this->returnValue($this->collectionFactory));
+
         $entity = $this->seed = $this->createEntity('Test', Test::class);
 
-        $this->collection = $this->getMockBuilder(EntityCollection::class)->disableOriginalConstructor()->getMock();
+        $this->account = $this->createEntity('Account', Entities\Account::class);
+        $this->team = $this->createEntity('Team', Entities\Team::class);
+
+        $this->collection = $this->createCollectionMock();
 
         $entityFactory
             ->method('create')
-            ->will($this->returnValue($entity));
+            ->will(
+                $this->returnCallback(
+                    function (string $entityType) {
+                        $className = 'Espo\\Entities\\' . ucfirst($entityType);
 
-        $this->repository = new Repository('Test', $entityManager, $entityFactory);
+                        return $this->createEntity($entityType, $className);
+                    }
+                )
+            );
 
-        $entityManager
+        $this->repository = $this->createRepository('Test');
+    }
+
+    protected function createCollectionMock() : EntityCollection
+    {
+        return $this->getMockBuilder(EntityCollection::class)->disableOriginalConstructor()->getMock();
+    }
+
+    protected function createRepository(string $entityType)
+    {
+        $repository = new Repository($entityType, $this->entityManager, $this->entityFactory);
+
+        $this->entityManager
             ->method('getRepository')
-            ->will($this->returnValue($this->repository));
+            ->will($this->returnValue($repository));
+
+        return $repository;
     }
 
     protected function createEntity(string $entityType, string $className)
@@ -76,6 +122,9 @@ class RDBRepositoryTest extends \PHPUnit\Framework\TestCase
         return new $className($entityType, [], $this->entityManager);
     }
 
+    /**
+     * @deprecated
+     */
     public function testFind()
     {
         $params = [
@@ -84,22 +133,23 @@ class RDBRepositoryTest extends \PHPUnit\Framework\TestCase
             ],
         ];
 
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'whereClause' => [
                 'name' => 'test',
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->find($params);
     }
 
-    public function testFindOne()
+    public function testFindOne1()
     {
         $params = [
             'whereClause' => [
@@ -107,239 +157,1043 @@ class RDBRepositoryTest extends \PHPUnit\Framework\TestCase
             ],
         ];
 
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'whereClause' => [
                 'name' => 'test',
             ],
             'offset' => 0,
             'limit' => 1,
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->findOne($params);
     }
 
-    public function testWhere1()
+    public function testFindOne2()
     {
-        $paramsExpected = [
-            'whereClause' => [
-                'name' => 'test',
-            ],
-        ];
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->where(['name' => 'test'])
+            ->limit(0, 1)
+            ->build();
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($select);
+
+        $this->repository->where(['name' => 'test'])->findOne();
+    }
+
+    public function testFindOne3()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->distinct()
+            ->from('Test')
+            ->where(['name' => 'test'])
+            ->limit(0, 1)
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('select')
+            ->will($this->returnValue($this->collection))
+            ->with($select);
+
+        $this->repository->distinct()->findOne([
+            'whereClause' => ['name' => 'test'],
+        ]);
+    }
+
+    /**
+     * @deprecated
+     */
+    public function testCount1()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->where(['name' => 'test'])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('count')
+            ->will($this->returnValue(1))
+            ->with($select);
+
+        $this->repository->count([
+            'whereClause' => ['name' => 'test'],
+        ]);
+    }
+
+    public function testCount2()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->where(['name' => 'test'])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('count')
+            ->will($this->returnValue(1))
+            ->with($select);
+
+        $this->repository->where(['name' => 'test'])->count();
+    }
+
+    public function testCount3()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('count')
+            ->will($this->returnValue(1))
+            ->with($select);
+
+        $this->repository->count();
+    }
+
+    public function testMax1()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('max')
+            ->will($this->returnValue(1))
+            ->with($select, 'test');
+
+        $this->repository->max('test');
+    }
+
+    public function testWhere1()
+    {
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
+            'whereClause' => [
+                'name' => 'test',
+            ],
+        ]);
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('select')
+            ->will($this->returnValue($this->collection))
+            ->with($paramsExpected);
 
         $this->repository->where(['name' => 'test'])->find();
     }
 
     public function testWhere2()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'whereClause' => [
-                ['name' => 'test'],
+                'name' => 'test',
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->where('name', 'test')->find();
     }
 
-    public function testWhereFineOne()
+    public function testWhereMerge()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'whereClause' => [
-                ['name' => 'test'],
+                'name2' => 'test2',
+                ['name1' => 'test1'],
             ],
-            'offset' => 0,
-            'limit' => 1,
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
+
+        $this->repository
+            ->where(['name1' => 'test1'])
+            ->find([
+                'whereClause' => ['name2' => 'test2'],
+            ]);
+    }
+
+    public function testWhereFineOne()
+    {
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
+            'whereClause' => [
+                'name' => 'test',
+            ],
+            'offset' => 0,
+            'limit' => 1,
+        ]);
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('select')
+            ->will($this->returnValue($this->collection))
+            ->with($paramsExpected);
 
         $this->repository->where('name', 'test')->findOne();
     }
 
     public function testJoin1()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'joins' => [
                 'Test',
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->join('Test')->find();
     }
 
     public function testJoin2()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'joins' => [
                 'Test1',
                 'Test2',
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->join(['Test1', 'Test2'])->find();
     }
 
     public function testJoin3()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'joins' => [
                 ['Test1', 'test1'],
                 ['Test2', 'test2'],
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->join([['Test1', 'test1'], ['Test2', 'test2']])->find();
     }
 
     public function testJoin4()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'joins' => [
                 ['Test1', 'test1', ['k' => 'v']],
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->join('Test1', 'test1', ['k' => 'v'])->find();
     }
 
     public function testLeftJoin1()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'leftJoins' => [
                 'Test',
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->leftJoin('Test')->find();
     }
 
     public function testMultipleLeftJoins()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'leftJoins' => [
                 'Test1',
                 ['Test2', 'test2'],
             ],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->leftJoin('Test1')->leftJoin('Test2', 'test2')->find();
     }
 
     public function testDistinct()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'distinct' => true,
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->distinct()->find();
     }
 
     public function testSth()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'returnSthCollection' => true,
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->sth()->find();
     }
 
     public function testOrder1()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'orderBy' => 'name',
             'order' => 'ASC',
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->order('name')->find();
     }
 
-    public function testSelect()
+    public function testSelect1()
     {
-        $paramsExpected = [
+        $paramsExpected = Select::fromRaw([
+            'from' => 'Test',
             'select' => ['name', 'date'],
-        ];
+        ]);
 
         $this->mapper
             ->expects($this->once())
             ->method('select')
             ->will($this->returnValue($this->collection))
-            ->with($this->seed, $paramsExpected);
+            ->with($paramsExpected);
 
         $this->repository->select(['name', 'date'])->find();
     }
+
+    public function testSelect2()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->select(['name'])
+            ->select('date')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('select')
+            ->will($this->returnValue($this->collection))
+            ->with($select);
+
+        $this->repository
+            ->select(['name'])
+            ->select('date')
+            ->find();
+    }
+
+    public function testFindRelated1()
+    {
+        $select = Select::fromRaw([
+            'from' => 'Team',
+        ]);
+
+        $this->account->id = 'accountId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue(new EntityCollection()))
+            ->with($this->account, 'teams', $select);
+
+        $this->createRepository('Account')->findRelated($this->account, 'teams');
+    }
+
+    public function testCountRelated1()
+    {
+        $select = Select::fromRaw([
+            'from' => 'Team',
+        ]);
+
+        $this->account->id = 'accountId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('countRelated')
+            ->will($this->returnValue(1))
+            ->with($this->account, 'teams', $select);
+
+        $this->createRepository('Account')->countRelated($this->account, 'teams');
+    }
+
+    public function testAdditionalColumns()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->select(['*', ['entityTeam.deleted', 'teamDeleted']])
+            ->build();
+
+        $this->account->id = 'accountId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue(new EntityCollection()))
+            ->with($this->account, 'teams', $select);
+
+        $this->createRepository('Account')->findRelated($this->account, 'teams', [
+            'additionalColumns' => [
+                'deleted' => 'teamDeleted',
+            ],
+        ]);
+    }
+
+    public function testAdditionalColumnsConditions()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->where([
+                'entityTeam.teamId' => 'testId',
+            ])
+            ->build();
+
+        $this->account->id = 'accountId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue(new EntityCollection()))
+            ->with($this->account, 'teams', $select);
+
+        $this->createRepository('Account')->findRelated($this->account, 'teams', [
+            'additionalColumnsConditions' => [
+                'teamId' => 'testId',
+            ],
+        ]);
+    }
+
+    public function testClone1()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->build();
+
+        $selectExpected = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->select('id')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('select')
+            ->will($this->returnValue(new EntityCollection()))
+            ->with($selectExpected);
+
+        $this->repository
+            ->clone($select)
+            ->select('id')
+            ->find();
+    }
+
+    public function testGetById1()
+    {
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Test')
+            ->where(['id' => '1'])
+            ->build();
+
+        $entity = $this->getMockBuilder(Entity::class)->getMock();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectOne')
+            ->will($this->returnValue($entity))
+            ->with($select);
+
+        $this->repository->getById('1');
+    }
+
+    public function testRelationInstance()
+    {
+        $repository = $this->createRepository('Account');
+
+        $account = $this->entityFactory->create('Account');
+        $account->id = 'accountId';
+
+        $relation = $repository->getRelation($account, 'teams');
+
+        $this->assertInstanceOf(RDBRelation::class, $relation);
+    }
+
+    public function testRelationCloneInstance()
+    {
+        $repository = $this->createRepository('Account');
+
+        $account = $this->entityFactory->create('Account');
+        $account->id = 'accountId';
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->build();
+
+        $relationSelectBuilder = $repository->getRelation($account, 'teams')->clone($select);
+
+        $this->assertInstanceOf(RDBRelationSelectBuilder::class, $relationSelectBuilder);
+    }
+
+    public function testRelationCloneBelongsToParentException()
+    {
+        $repository = $this->createRepository('Note');
+
+        $note = $this->entityFactory->create('Note');
+        $note->id = 'noteId';
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Post')
+            ->build();
+
+        $this->expectException(RuntimeException::class);
+
+        $relationSelectBuilder = $repository->getRelation($note, 'parent')->clone($select);
+    }
+
+    public function testRelationCount()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Comment')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('countRelated')
+            ->will($this->returnValue(1))
+            ->with($post, 'comments', $select);
+
+        $this->createRepository('Post')->getRelation($post, 'comments')->count();
+    }
+
+    public function testRelationFindHasMany()
+    {
+        $repository = $this->createRepository('Post');
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Comment')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($post, 'comments', $select);
+
+        $relationSelectBuilder = $repository->getRelation($post, 'comments')->find();
+    }
+
+    public function testRelationFindBelongsTo()
+    {
+        $comment = $this->entityFactory->create('Comment');
+        $comment->id = 'commentId';
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Post')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($post))
+            ->with($comment, 'post', $select);
+
+        $result = $this->createRepository('Comment')
+            ->getRelation($comment, 'post')
+            ->find();
+
+        $this->assertEquals(1, count($result));
+
+        $this->assertEquals($post, $result[0]);
+    }
+
+    public function testRelationFindBelongsToParent()
+    {
+        $note = $this->entityFactory->create('Note');
+        $note->id = 'noteId';
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'noteId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($post))
+            ->with($note, 'parent',);
+
+        $result = $this->createRepository('Note')->getRelation($note, 'parent')->find();
+
+        $this->assertEquals(1, count($result));
+
+        $this->assertEquals($post, $result[0]);
+    }
+
+    public function testRelationFindOneBelongsToParent()
+    {
+        $note = $this->entityFactory->create('Note');
+        $note->id = 'noteId';
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($post))
+            ->with($note, 'parent');
+
+        $result = $this->createRepository('Note')->getRelation($note, 'parent')->findOne();
+
+        $this->assertEquals($post, $result);
+    }
+
+    public function testRelationIsRelated1()
+    {
+        $note = $this->entityFactory->create('Note');
+        $note->set('id', 'noteId');
+
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $note->set('parentId', $post->id);
+        $note->set('parentType', 'Post');
+
+        $result = $this->createRepository('Note')->getRelation($note, 'parent')->isRelated($post);
+
+        $this->assertTrue($result);
+
+        $note->set('parentId', 'anotherId');
+        $note->set('parentType', 'Post');
+
+        $result = $this->createRepository('Note')->getRelation($note, 'parent')->isRelated($post);
+
+        $this->assertFalse($result);
+    }
+
+    public function testRelationIsRelated2()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $note = $this->entityFactory->create('Note');
+        $note->set('id', 'noteId');
+
+        $collection = $this->collectionFactory->create('Note', [$note]);
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Note')
+            ->select(['id'])
+            ->where(['id' => $note->id])
+            ->limit(0, 1)
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($post, 'notes', $select);
+
+        $result = $this->createRepository('Post')->getRelation($post, 'notes')->isRelated($note);
+
+        $this->assertTrue($result);
+    }
+
+    public function testRelationIsRelated3()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $note = $this->entityFactory->create('Note');
+        $note->set('id', 'noteId');
+
+        $collection = $this->collectionFactory->create('Note', []);
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Note')
+            ->select(['id'])
+            ->where(['id' => $note->id])
+            ->limit(0, 1)
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($post, 'notes', $select);
+
+        $result = $this->createRepository('Post')->getRelation($post, 'notes')->isRelated($note);
+
+        $this->assertFalse($result);
+    }
+
+    public function testRelate1()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $note = $this->entityFactory->create('Note');
+        $note->set('id', 'noteId');
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('relateById')
+            ->with($post, 'notes', $note->id);
+
+        $this->createRepository('Post')->getRelation($post, 'notes')->relate($note);
+    }
+
+    public function testUnrelate1()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $note = $this->entityFactory->create('Note');
+        $note->set('id', 'noteId');
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('unrelateById')
+            ->with($post, 'notes', $note->id);
+
+        $this->createRepository('Post')->getRelation($post, 'notes')->unrelate($note);
+    }
+
+    public function testMassRelate()
+    {
+        $post = $this->entityFactory->create('Post');
+        $post->set('id', 'postId');
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Note')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('massRelate')
+            ->with($post, 'notes', $select);
+
+        $this->createRepository('Post')->getRelation($post, 'notes')->massRelate($select);
+    }
+
+    public function testGetColumn()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $team = $this->entityFactory->create('Team');
+        $team->set('id', 'teamId');
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('getRelationColumn')
+            ->with($account, 'teams', $team->id, 'test');
+
+        $this->createRepository('Post')->getRelation($account, 'teams')->getColumn($team, 'test');
+    }
+
+    public function testUpdateColumns()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $team = $this->entityFactory->create('Team');
+        $team->set('id', 'teamId');
+
+        $columns = [
+            'column' => 'test',
+        ];
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('updateRelationColumns')
+            ->with($account, 'teams', $team->id, $columns);
+
+        $this->createRepository('Post')->getRelation($account, 'teams')->updateColumns($team, $columns);
+    }
+
+    public function testRelationSelectBuilderFind()
+    {
+        $repository = $this->createRepository('Post');
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $collection = $this->createCollectionMock();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Comment')
+            ->select(['id'])
+            ->distinct()
+            ->where(['name' => 'test'])
+            ->join('Test', 'test', ['id:' => 'id'])
+            ->order('id', 'DESC')
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($post, 'comments', $select);
+
+        $repository->getRelation($post, 'comments')
+            ->select(['id'])
+            ->distinct()
+            ->where(['name' => 'test'])
+            ->join('Test', 'test', ['id:' => 'id'])
+            ->order('id', 'DESC')
+            ->find();
+    }
+
+    public function testRelationSelectBuilderFindOne()
+    {
+        $repository = $this->createRepository('Post');
+
+        $post = $this->entityFactory->create('Post');
+        $post->id = 'postId';
+
+        $collection = $this->collectionFactory->create();
+
+        $comment = $this->entityFactory->create('Comment');
+        $comment->set('id', 'commentId');
+
+        $collection[] = $comment;
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Comment')
+            ->select(['id'])
+            ->distinct()
+            ->where(['name' => 'test'])
+            ->join('Test', 'test', ['id:' => 'id'])
+            ->order('id', 'DESC')
+            ->limit(0, 1)
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($post, 'comments', $select);
+
+        $result = $repository->getRelation($post, 'comments')
+            ->select(['id'])
+            ->distinct()
+            ->where(['name' => 'test'])
+            ->join('Test', 'test', ['id:' => 'id'])
+            ->order('id', 'DESC')
+            ->findOne();
+
+        $this->assertEquals($comment, $result);
+    }
+
+    public function testRelationSelectBuilderColumns1()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->select(['*', ['entityTeam.deleted', 'test']])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($account, 'teams', $select);
+
+        $this->createRepository('Account')->getRelation($account, 'teams')
+            ->columns(['deleted' => 'test'])
+            ->find();
+    }
+
+    public function testRelationSelectBuilderColumns2()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->select(['id', ['entityTeam.deleted', 'test']])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($account, 'teams', $select);
+
+        $this->createRepository('Account')->getRelation($account, 'teams')
+            ->select(['id'])
+            ->columns(['deleted' => 'test'])
+            ->find();
+    }
+
+    public function testRelationSelectBuilderColumnsWhere1()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->where(['entityTeam.deleted' => false])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($account, 'teams', $select);
+
+
+        $this->createRepository('Account')->getRelation($account, 'teams')
+            ->columnsWhere(['deleted' => false])
+            ->find();
+    }
+
+    public function testRelationSelectBuilderColumnsWhere2()
+    {
+        $account = $this->entityFactory->create('Account');
+        $account->set('id', 'accountId');
+
+        $collection = $this->collectionFactory->create();
+
+        $select = $this->queryBuilder
+            ->select()
+            ->from('Team')
+            ->where([
+                'OR' => [
+                    ['entityTeam.deleted' => false],
+                    ['entityTeam.deleted' => null],
+                ]
+            ])
+            ->build();
+
+        $this->mapper
+            ->expects($this->once())
+            ->method('selectRelated')
+            ->will($this->returnValue($collection))
+            ->with($account, 'teams', $select);
+
+
+        $this->createRepository('Account')->getRelation($account, 'teams')
+            ->columnsWhere([
+                'OR' => [
+                    ['deleted' => false],
+                    ['deleted' => null],
+                ]
+            ])
+            ->find();
+    }
 }
diff --git a/tests/unit/testData/DB/Entities.php b/tests/unit/testData/DB/Entities.php
index fc91c9a16a..224293a057 100644
--- a/tests/unit/testData/DB/Entities.php
+++ b/tests/unit/testData/DB/Entities.php
@@ -12,23 +12,23 @@ class TEntity extends BaseEntity
 
 class Account extends TEntity
 {
-    public $fields = array(
-            'id' => array(
+    public $fields = [
+            'id' => [
                 'type' => Entity::ID,
-            ),
-            'name' => array(
+            ],
+            'name' => [
                 'type' => Entity::VARCHAR,
                 'len' => 255,
-            ),
-            'deleted' => array(
+            ],
+            'deleted' => [
                 'type' => Entity::BOOL,
                 'default' => 0,
-            ),
+            ],
             'stub' => [
                 'type' => 'varchar',
                 'notStorable' => true,
             ],
-    );
+    ];
     public $relations = [
         'teams' => [
             'type' => Entity::MANY_MANY,
@@ -38,26 +38,26 @@ class Account extends TEntity
                 'entityId',
                 'teamId',
             ],
-            'conditions' => ['entityType' => 'Account']
+            'conditions' => ['entityType' => 'Account'],
         ],
     ];
 }
 
 class Team extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID,
-        ),
-        'name' => array(
+        ],
+        'name' => [
             'type' => Entity::VARCHAR,
             'len' => 255,
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0,
-        ),
-    );
+        ],
+    ];
     public $relations = [];
 }
 
@@ -90,133 +90,134 @@ class EntityTeam extends TEntity
 
 class Contact extends TEntity
 {
-    public $fields = array(
-            'id' => array(
+    public $fields = [
+            'id' => [
                 'type' => Entity::ID,
-            ),
-            'name' => array(
+            ],
+            'name' => [
                 'type' => Entity::VARCHAR,
                 'notStorable' => true,
                 'select' => "TRIM(CONCAT(contact.first_name, ' ', contact.last_name))",
-                'where' => array(
-                    'LIKE' => "(contact.first_name LIKE {value} OR contact.last_name LIKE {value} OR CONCAT(contact.first_name, ' ', contact.last_name) LIKE {value})",
-                ),
+                'where' => [
+                    'LIKE' => "(contact.first_name LIKE {value} OR contact.last_name LIKE {value} OR "
+                        ."CONCAT(contact.first_name, ' ', contact.last_name) LIKE {value})",
+                ],
                 'orderBy' => "contact.first_name {direction}, contact.last_name {direction}",
-            ),
-            'firstName' => array(
+            ],
+            'firstName' => [
                 'type' => Entity::VARCHAR,
-            ),
-            'lastName' => array(
+            ],
+            'lastName' => [
                 'type' => Entity::VARCHAR,
-            ),
-            'deleted' => array(
+            ],
+            'deleted' => [
                 'type' => Entity::BOOL,
                 'default' => 0,
-            ),
-    );
-    public $relations = array();
+            ],
+    ];
+    public $relations = [];
 }
 
 class Post extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID,
-        ),
-        'name' => array(
+        ],
+        'name' => [
             'type' => Entity::VARCHAR,
             'len' => 255,
-        ),
-        'privateField' => array(
+        ],
+        'privateField' => [
             'notStorable' => true,
-        ),
-        'createdByName' => array(
+        ],
+        'createdByName' => [
             'type' => Entity::FOREIGN,
             'relation' => 'createdBy',
-            'foreign' => array('salutationName', 'firstName', ' ', 'lastName'),
-        ),
-        'createdById' => array(
+            'foreign' => ['salutationName', 'firstName', ' ', 'lastName'],
+        ],
+        'createdById' => [
             'type' => Entity::FOREIGN_ID,
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0,
-        ),
-    );
-    public $relations = array(
-        'tags' => array(
+        ],
+    ];
+    public $relations = [
+        'tags' => [
             'type' => Entity::MANY_MANY,
             'entity' => 'Tag',
             'relationName' => 'PostTag',
             'key' => 'id',
             'foreignKey' => 'id',
-            'midKeys' => array(
+            'midKeys' => [
                 'postId',
                 'tagId',
-            ),
+            ],
             'additionalColumns' => [
                 'role' => [
                     'type' => Entity::VARCHAR,
                 ],
             ],
-        ),
-        'comments' => array(
+        ],
+        'comments' => [
             'type' => Entity::HAS_MANY,
             'entity' => 'Comment',
             'foreignKey' => 'postId',
-        ),
-        'createdBy' => array(
+        ],
+        'createdBy' => [
             'type' => Entity::BELONGS_TO,
             'entity' => 'User',
             'key' => 'createdById',
-        ),
-        'notes' => array(
+        ],
+        'notes' => [
             'type' => Entity::HAS_CHILDREN,
             'entity' => 'Note',
             'foreignKey' => 'parentId',
             'foreignType' => 'parentType',
-        ),
+        ],
         'postData' => [
             'type' => Entity::HAS_ONE,
             'entity' => 'PostData',
             'foreign' => 'post',
             'noJoin' => true,
         ],
-    );
+    ];
 }
 
 class Comment extends TEntity
 {
-    public $fields = array(
-            'id' => array(
-                'type' => Entity::ID,
-            ),
-            'postId' => array(
-                'type' => Entity::FOREIGN_ID,
-            ),
-            'postName' => array(
-                'type' => Entity::FOREIGN,
-                'relation' => 'post',
-                'foreign' => 'name',
-            ),
-            'name' => array(
-                'type' => Entity::VARCHAR,
-                'len' => 255,
-            ),
-            'deleted' => array(
-                'type' => Entity::BOOL,
-                'default' => 0,
-            ),
-    );
+    public $fields = [
+        'id' => [
+            'type' => Entity::ID,
+        ],
+        'postId' => [
+            'type' => Entity::FOREIGN_ID,
+        ],
+        'postName' => [
+            'type' => Entity::FOREIGN,
+            'relation' => 'post',
+            'foreign' => 'name',
+        ],
+        'name' => [
+            'type' => Entity::VARCHAR,
+            'len' => 255,
+        ],
+        'deleted' => [
+            'type' => Entity::BOOL,
+            'default' => 0,
+        ],
+    ];
 
-    public $relations = array(
-            'post' => array(
-                'type' => Entity::BELONGS_TO,
-                'entity' => 'Post',
-                'key' => 'postId',
-                'foreignKey' => 'id',
-            ),
-    );
+    public $relations = [
+        'post' => [
+            'type' => Entity::BELONGS_TO,
+            'entity' => 'Post',
+            'key' => 'postId',
+            'foreignKey' => 'id',
+        ],
+    ];
 }
 
 class PostData extends TEntity
@@ -247,19 +248,19 @@ class PostData extends TEntity
 
 class Tag extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID,
-        ),
-        'name' => array(
+        ],
+        'name' => [
             'type' => Entity::VARCHAR,
             'len' => 50,
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0,
-        ),
-    );
+        ],
+    ];
 }
 
 class PostTag extends TEntity
@@ -290,29 +291,29 @@ class PostTag extends TEntity
 
 class Note extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID,
-        ),
-        'name' => array(
+        ],
+        'name' => [
             'type' => Entity::VARCHAR,
             'len' => 50,
-        ),
-        'parentId' => array(
+        ],
+        'parentId' => [
             'type' => Entity::FOREIGN_ID,
-        ),
-        'parentType' => array(
+        ],
+        'parentType' => [
             'type' => Entity::FOREIGN_TYPE,
-        ),
-        'parentName' => array(
+        ],
+        'parentName' => [
             'type' => Entity::VARCHAR,
             'notStorable' => true,
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0,
-        ),
-    );
+        ],
+    ];
 
     public $relations = [
         'parent' => [
@@ -326,49 +327,82 @@ class Note extends TEntity
 
 class Article extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID
-        ),
-        'name' => array(
+        ],
+        'name' => [
             'type' => Entity::VARCHAR,
             'len' => 50,
-        ),
-        'description' => array(
+        ],
+        'description' => [
             'type' => Entity::TEXT
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0
-        )
-    );
+        ]
+    ];
 }
 
-
 class Job extends TEntity
 {
-    public $fields = array(
-        'id' => array(
+    public $fields = [
+        'id' => [
             'type' => Entity::ID
-        ),
-        'string' => array(
+        ],
+        'string' => [
             'type' => Entity::VARCHAR,
             'len' => 50
-        ),
-        'array' => array(
+        ],
+        'array' => [
             'type' => Entity::JSON_ARRAY
-        ),
-        'arrayUnordered' => array(
+        ],
+        'arrayUnordered' => [
             'type' => Entity::JSON_ARRAY,
             'isUnordered' => true
-        ),
-        'object' => array(
+        ],
+        'object' => [
             'type' => Entity::JSON_OBJECT
-        ),
-        'deleted' => array(
+        ],
+        'deleted' => [
             'type' => Entity::BOOL,
             'default' => 0
-        )
-    );
+        ],
+    ];
 }
 
+class Test extends TEntity
+{
+    public $fields = [
+        'id' => [
+            'type' => Entity::ID,
+        ],
+        'name' => [
+            'type' => Entity::VARCHAR,
+            'len' => 255,
+        ],
+        'date' => [
+            'type' => Entity::DATE
+        ],
+        'dateTime' => [
+            'type' => Entity::DATETIME
+        ],
+        'int' => [
+            'type' => Entity::INT
+        ],
+        'float' => [
+            'type' => Entity::FLOAT
+        ],
+        'list' => [
+            'type' => Entity::JSON_ARRAY
+        ],
+        'object' => [
+            'type' => Entity::JSON_OBJECT
+        ],
+        'deleted' => [
+            'type' => Entity::BOOL,
+            'default' => 0,
+        ]
+    ];
+}