diff --git a/application/Espo/ORM/Query/Part/Condition.php b/application/Espo/ORM/Query/Part/Condition.php
index 39b42a6219..cc618d5e31 100644
--- a/application/Espo/ORM/Query/Part/Condition.php
+++ b/application/Espo/ORM/Query/Part/Condition.php
@@ -91,10 +91,13 @@ class Condition
      * Create '=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float|bool|null $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float|bool|null $argument2 A scalar, expression or sub-query.
      */
-    public static function equal(Expression $argument1, Expression|string|int|float|bool|null $argument2): Comparison
-    {
+    public static function equal(
+        Expression $argument1,
+        Expression|Select|string|int|float|bool|null $argument2
+    ): Comparison {
+
         return Comparison::equal($argument1, $argument2);
     }
 
@@ -102,10 +105,13 @@ class Condition
      * Create '!=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float|bool|null $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float|bool|null $argument2 A scalar, expression or sub-query.
      */
-    public static function notEqual(Expression $argument1, Expression|string|int|float|bool|null $argument2): Comparison
-    {
+    public static function notEqual(
+        Expression $argument1,
+        Expression|Select|string|int|float|bool|null $argument2
+    ): Comparison {
+
         return Comparison::notEqual($argument1, $argument2);
     }
 
@@ -135,10 +141,13 @@ class Condition
      * Create '>' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      */
-    public static function greater(Expression $argument1, Expression|string|int|float $argument2): Comparison
-    {
+    public static function greater(
+        Expression $argument1,
+        Expression|Select|string|int|float $argument2
+    ): Comparison {
+
         return Comparison::greater($argument1, $argument2);
     }
 
@@ -146,10 +155,13 @@ class Condition
      * Create '>=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      */
-    public static function greaterOrEqual(Expression $argument1, Expression|string|int|float $argument2): Comparison
-    {
+    public static function greaterOrEqual(
+        Expression $argument1,
+        Expression|Select|string|int|float $argument2
+    ): Comparison {
+
         return Comparison::greaterOrEqual($argument1, $argument2);
     }
 
@@ -157,10 +169,13 @@ class Condition
      * Create '<' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      */
-    public static function less(Expression $argument1, Expression|string|int|float $argument2): Comparison
-    {
+    public static function less(
+        Expression $argument1,
+        Expression|Select|string|int|float $argument2
+    ): Comparison {
+
         return Comparison::less($argument1, $argument2);
     }
 
@@ -168,10 +183,13 @@ class Condition
      * Create '<=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      */
-    public static function lessOrEqual(Expression $argument1, Expression|string|int|float $argument2): Comparison
-    {
+    public static function lessOrEqual(
+        Expression $argument1,
+        Expression|Select|string|int|float $argument2
+    ): Comparison {
+
         return Comparison::lessOrEqual($argument1, $argument2);
     }
 
diff --git a/application/Espo/ORM/Query/Part/Where/Comparison.php b/application/Espo/ORM/Query/Part/Where/Comparison.php
index 9751d6dd09..564ecebd43 100644
--- a/application/Espo/ORM/Query/Part/Where/Comparison.php
+++ b/application/Espo/ORM/Query/Part/Where/Comparison.php
@@ -81,11 +81,14 @@ class Comparison implements WhereItem
      * Create '=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float|bool|null $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float|bool|null $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function equal(Expression $argument1, Expression|string|int|float|bool|null $argument2): self
-    {
+    public static function equal(
+        Expression $argument1,
+        Expression|Select|string|int|float|bool|null $argument2
+    ): self {
+
         return self::createComparison(self::OPERATOR_EQUAL, $argument1, $argument2);
     }
 
@@ -93,11 +96,14 @@ class Comparison implements WhereItem
      * Create '!=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float|bool|null $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float|bool|null $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function notEqual(Expression $argument1, Expression|string|int|float|bool|null $argument2): self
-    {
+    public static function notEqual(
+        Expression $argument1,
+        Expression|Select|string|int|float|bool|null $argument2
+    ): self {
+
         return self::createComparison(self::OPERATOR_NOT_EQUAL, $argument1, $argument2);
     }
 
@@ -129,10 +135,10 @@ class Comparison implements WhereItem
      * Create '>' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function greater(Expression $argument1, Expression|string|int|float $argument2): self
+    public static function greater(Expression $argument1, Expression|Select|string|int|float $argument2): self
     {
         return self::createComparison(self::OPERATOR_GREATER, $argument1, $argument2);
     }
@@ -141,10 +147,10 @@ class Comparison implements WhereItem
      * Create '>=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function greaterOrEqual(Expression $argument1, Expression|string|int|float $argument2): self
+    public static function greaterOrEqual(Expression $argument1, Expression|Select|string|int|float $argument2): self
     {
         return self::createComparison(self::OPERATOR_GREATER_OR_EQUAL, $argument1, $argument2);
     }
@@ -153,10 +159,10 @@ class Comparison implements WhereItem
      * Create '<' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function less(Expression $argument1, Expression|string|int|float $argument2): self
+    public static function less(Expression $argument1, Expression|Select|string|int|float $argument2): self
     {
         return self::createComparison(self::OPERATOR_LESS, $argument1, $argument2);
     }
@@ -165,10 +171,10 @@ class Comparison implements WhereItem
      * Create '<=' comparison.
      *
      * @param Expression $argument1 An expression.
-     * @param Expression|string|int|float $argument2 A value (if scalar) or expression.
+     * @param Expression|Select|string|int|float $argument2 A scalar, expression or sub-query.
      * @return self
      */
-    public static function lessOrEqual(Expression $argument1, Expression|string|int|float $argument2): self
+    public static function lessOrEqual(Expression $argument1, Expression|Select|string|int|float $argument2): self
     {
         return self::createComparison(self::OPERATOR_LESS_OR_EQUAL, $argument1, $argument2);
     }
@@ -208,7 +214,7 @@ class Comparison implements WhereItem
     private static function createComparison(
         string $operator,
         Expression|string $argument1,
-        Expression|string|int|float|bool|null $argument2
+        Expression|Select|string|int|float|bool|null $argument2
     ): self {
 
         if (is_string($argument1)) {
diff --git a/application/Espo/ORM/QueryComposer/BaseQueryComposer.php b/application/Espo/ORM/QueryComposer/BaseQueryComposer.php
index f565252703..dc4f4b1545 100644
--- a/application/Espo/ORM/QueryComposer/BaseQueryComposer.php
+++ b/application/Espo/ORM/QueryComposer/BaseQueryComposer.php
@@ -2462,6 +2462,7 @@ abstract class BaseQueryComposer implements QueryComposer
             return $this->quote(false);
         }
 
+        // @todo Operators (<s, >s, <=s, =>s) producing 'operator ANY (sub-query)'.
         if ($operatorOrm === '=s' || $operatorOrm === '!=s') {
             if ($value instanceof Select) {
                 $subSql = $this->composeSelect($value);
@@ -2494,6 +2495,16 @@ abstract class BaseQueryComposer implements QueryComposer
             return "{$leftPart} {$operator} ({$subSql})";
         }
 
+        if ($value instanceof Select) {
+            if ($operatorOrm === '*' || $operatorOrm === '!*') {
+                throw new RuntimeException("LIKE operator is not compatible with sub-query.");
+            }
+
+            $subQueryPart = $this->composeSelect($value);
+
+            return "{$leftPart} {$operator} ({$subQueryPart})";
+        }
+
         if (is_array($value)) {
             $valuePartList = $value;
 
diff --git a/tests/unit/Espo/ORM/MysqlQueryComposerTest.php b/tests/unit/Espo/ORM/MysqlQueryComposerTest.php
index 5e435cb356..42caf28290 100644
--- a/tests/unit/Espo/ORM/MysqlQueryComposerTest.php
+++ b/tests/unit/Espo/ORM/MysqlQueryComposerTest.php
@@ -1136,6 +1136,58 @@ class MysqlQueryComposerTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals($expectedSql, $sql);
     }
 
+    public function testSelectWithSubquery5()
+    {
+        $subQuery = SelectBuilder::create()
+            ->from('Post')
+            ->select('id')
+            ->where(['name' => 'test'])
+            ->build();
+
+        $sql = $this->query->composeSelect(
+            SelectBuilder::create()
+                ->from('Post')
+                ->select('id')
+                ->where(
+                    Comparison::equal(Expression::value('1'), $subQuery)
+                )
+                ->build()
+        );
+
+        $expectedSql =
+            "SELECT post.id AS `id` FROM `post` ".
+            "WHERE '1' = (SELECT post.id AS `id` FROM `post` ".
+            "WHERE post.name = 'test' AND post.deleted = 0) AND post.deleted = 0";
+
+        $this->assertEquals($expectedSql, $sql);
+    }
+
+    public function testSelectWithSubquery6()
+    {
+        $subQuery = SelectBuilder::create()
+            ->from('Post')
+            ->select('id')
+            ->where(['name' => 'test'])
+            ->build();
+
+        $sql = $this->query->composeSelect(
+            SelectBuilder::create()
+                ->from('Post')
+                ->select('id')
+                ->where(
+                    Comparison::greaterOrEqual(Expression::value('1'), $subQuery)
+                )
+                ->build()
+        );
+
+        $expectedSql =
+            "SELECT post.id AS `id` FROM `post` ".
+            "WHERE '1' >= (SELECT post.id AS `id` FROM `post` ".
+            "WHERE post.name = 'test' AND post.deleted = 0) AND post.deleted = 0";
+
+        $this->assertEquals($expectedSql, $sql);
+    }
+
     public function testSelectExists1(): void
     {
         $expectedSql =