diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Gateway/DoctrineDatabaseTest.php
index 5e36d1c03a..4d8afe35b1 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Gateway/DoctrineDatabaseTest.php
@@ -61,8 +61,8 @@ public function testInsertContentObject()
                     'status' => ContentInfo::STATUS_DRAFT,
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'name',
@@ -154,7 +154,7 @@ protected function getVersionFixture()
         $version->status = 0;
         $version->creationDate = 1312278322;
         $version->modificationDate = 1312278323;
-        $version->initialLanguageCode = 'eng-GB';
+        $version->initialLanguageCode = self::ENG_GB;
         $version->contentInfo = new ContentInfo(
             [
                 'id' => 2342,
@@ -192,8 +192,8 @@ public function testInsertVersion()
                     // 'user_id',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'contentobject_id',
@@ -232,8 +232,8 @@ public function testSetStatus()
 
         $this->assertQueryResult(
             [[VersionInfo::STATUS_PENDING]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select('status')
                 ->from('ezcontentobject_version')
         );
@@ -241,8 +241,8 @@ public function testSetStatus()
         // check that content status has not been set to published
         $this->assertQueryResult(
             [[VersionInfo::STATUS_DRAFT]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select('status')
                 ->from('ezcontentobject')
         );
@@ -270,8 +270,8 @@ public function testSetStatusPublished()
 
         $this->assertQueryResult(
             [[VersionInfo::STATUS_PUBLISHED]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select('status')
                 ->from('ezcontentobject_version')
         );
@@ -279,8 +279,8 @@ public function testSetStatusPublished()
         // check that content status has been set to published
         $this->assertQueryResult(
             [[ContentInfo::STATUS_PUBLISHED]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select('status')
                 ->from('ezcontentobject')
         );
@@ -324,7 +324,7 @@ public function testUpdateContent()
                     'name' => 'Thoth',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'initial_language_id',
                     'modified',
@@ -384,7 +384,8 @@ public function testUpdateVersion()
 
         $gateway->updateVersion(10, 2, $this->getUpdateStructFixture());
 
-        $query = $this->getDatabaseHandler()->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
+        $expr = $query->expr();
         $this->assertQueryResult(
             [
                 [
@@ -402,9 +403,9 @@ public function testUpdateVersion()
                     ]
                 )->from('ezcontentobject_version')
                 ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 10),
-                        $query->expr->eq('version', 2)
+                    $expr->andX(
+                        $expr->eq('contentobject_id', 10),
+                        $expr->eq('version', 2)
                     )
                 )
         );
@@ -433,15 +434,15 @@ public function testInsertNewField()
                     'data_int' => '42',
                     'data_text' => 'Test text',
                     'data_type_string' => 'ezstring',
-                    'language_code' => 'eng-GB',
+                    'language_code' => self::ENG_GB,
                     'language_id' => '4',
                     'sort_key_int' => '23',
                     'sort_key_string' => 'Test',
                     'version' => '1',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'contentclassattribute_id',
@@ -468,7 +469,7 @@ public function testInsertNewAlwaysAvailableField()
         $content = $this->getContentFixture();
         $content->versionInfo->contentInfo->id = 2342;
         // Set main language to the one used in the field fixture
-        $content->versionInfo->contentInfo->mainLanguageCode = 'eng-GB';
+        $content->versionInfo->contentInfo->mainLanguageCode = self::ENG_GB;
 
         $field = $this->getFieldFixture();
         $value = $this->getStorageValueFixture();
@@ -485,15 +486,15 @@ public function testInsertNewAlwaysAvailableField()
                     'data_int' => '42',
                     'data_text' => 'Test text',
                     'data_type_string' => 'ezstring',
-                    'language_code' => 'eng-GB',
+                    'language_code' => self::ENG_GB,
                     'language_id' => '5',
                     'sort_key_int' => '23',
                     'sort_key_string' => 'Test',
                     'version' => '1',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'contentclassattribute_id',
@@ -549,8 +550,8 @@ public function testUpdateField()
                     'sort_key_string' => 'new_text',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'data_float',
@@ -612,8 +613,8 @@ public function testUpdateNonTranslatableField()
                     'sort_key_string' => 'new_text',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'data_float',
@@ -732,7 +733,7 @@ public function testLoadWithAllTranslations()
 
         $this->assertValuesInRows(
             'ezcontentobject_attribute_language_code',
-            ['eng-US', 'eng-GB'],
+            ['eng-US', self::ENG_GB],
             $res
         );
 
@@ -805,11 +806,11 @@ public function testLoadWithSingleTranslation()
         );
 
         $gateway = $this->getDatabaseGateway();
-        $res = $gateway->load(226, 2, ['eng-GB']);
+        $res = $gateway->load(226, 2, [self::ENG_GB]);
 
         $this->assertValuesInRows(
             'ezcontentobject_attribute_language_code',
-            ['eng-GB'],
+            [self::ENG_GB],
             $res
         );
         $this->assertValuesInRows(
@@ -1183,11 +1184,11 @@ public function testSetName()
 
         $gateway = $this->getDatabaseGateway();
 
-        $gateway->setName(14, 2, 'Hello world!', 'eng-GB');
+        $gateway->setName(14, 2, 'Hello world!', self::ENG_GB);
 
-        $query = $this->getDatabaseHandler()->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
-            [['eng-GB', 2, 14, 4, 'Hello world!', 'eng-GB']],
+            [[self::ENG_GB, 2, 14, 4, 'Hello world!', self::ENG_GB]],
             $query
                 ->select(
                     [
@@ -1200,13 +1201,12 @@ public function testSetName()
                     ]
                 )
                 ->from('ezcontentobject_name')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 14),
-                        $query->expr->eq('content_version', 2),
-                        $query->expr->eq('content_translation', $query->bindValue('eng-GB'))
-                    )
-                )
+                ->where('contentobject_id = :content_id')
+                ->andWhere('content_version = :version_no')
+                ->andWhere('content_translation = :language_code')
+                ->setParameter('content_id', 14, ParameterType::INTEGER)
+                ->setParameter('version_no', 2, ParameterType::INTEGER)
+                ->setParameter('language_code', self::ENG_GB, ParameterType::STRING)
         );
     }
 
@@ -1482,8 +1482,8 @@ public function testInsertRelation()
                     'relation_type' => $struct->type,
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()
+                ->createQueryBuilder()
                 ->select(
                     [
                         'id',
@@ -2007,7 +2007,7 @@ protected function getFieldFixture()
 
         $field->fieldDefinitionId = 231;
         $field->type = 'ezstring';
-        $field->languageCode = 'eng-GB';
+        $field->languageCode = self::ENG_GB;
         $field->versionNo = 1;
 
         return $field;
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Language/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Language/Gateway/DoctrineDatabaseTest.php
index 95d5253137..6a666c7aef 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Language/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Language/Gateway/DoctrineDatabaseTest.php
@@ -52,7 +52,7 @@ public function testInsertLanguage()
                     'disabled' => '0',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('id', 'locale', 'name', 'disabled')
                 ->from('ezcontent_language')
                 ->where('id=8')
@@ -97,7 +97,7 @@ public function testUpdateLanguage()
                     'disabled' => '0',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('id', 'locale', 'name', 'disabled')
                 ->from('ezcontent_language')
                 ->where('id=2')
@@ -171,7 +171,7 @@ public function testDeleteLanguage()
                     'count' => '1',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * ) AS count')
                 ->from('ezcontent_language')
         );
@@ -182,7 +182,7 @@ public function testDeleteLanguage()
                     'count' => '0',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * ) AS count')
                 ->from('ezcontent_language')
                 ->where('id=2')
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/LanguageAwareTestCase.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/LanguageAwareTestCase.php
index 9287bafe7c..7288fed7b2 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/LanguageAwareTestCase.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/LanguageAwareTestCase.php
@@ -1,8 +1,6 @@
 <?php
 
 /**
- * File contains: eZ\Publish\Core\Persistence\Legacy\Tests\Content\LanguageAwareTestCase class.
- *
  * @copyright Copyright (C) eZ Systems AS. All rights reserved.
  * @license For full copyright and license information view LICENSE file distributed with this source code.
  */
@@ -20,6 +18,8 @@
  */
 abstract class LanguageAwareTestCase extends TestCase
 {
+    protected const ENG_GB = 'eng-GB';
+
     /**
      * Language handler.
      *
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTest.php
index 1b1e2853d5..db0e90812c 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTest.php
@@ -1,19 +1,20 @@
 <?php
 
 /**
- * File contains: eZ\Publish\Core\Persistence\Legacy\Tests\Content\Location\Gateway\DoctrineDatabaseTest class.
- *
  * @copyright Copyright (C) eZ Systems AS. All rights reserved.
  * @license For full copyright and license information view LICENSE file distributed with this source code.
  */
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\Content\Location\Gateway;
 
+use Doctrine\DBAL\FetchMode;
 use Doctrine\DBAL\ParameterType;
+use eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway;
 use eZ\Publish\Core\Persistence\Legacy\Tests\Content\LanguageAwareTestCase;
 use eZ\Publish\SPI\Persistence\Content\Location;
 use eZ\Publish\SPI\Persistence\Content\Location\CreateStruct;
 use eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase;
 use eZ\Publish\Core\Base\Exceptions\NotFoundException;
+use Doctrine\DBAL\Query\QueryBuilder;
 
 /**
  * Test case for eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase.
@@ -62,8 +63,8 @@ private function assertLoadLocationProperties(array $locationData): void
     public function testLoadLocationByRemoteId()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $data = $handler->getBasicNodeDataByRemoteId('dbc2f3c8716c12f32c379dbf0b1cb133');
+        $gateway = $this->getLocationGateway();
+        $data = $gateway->getBasicNodeDataByRemoteId('dbc2f3c8716c12f32c379dbf0b1cb133');
 
         self::assertLoadLocationProperties($data);
     }
@@ -71,8 +72,8 @@ public function testLoadLocationByRemoteId()
     public function testLoadLocation()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $data = $handler->getBasicNodeData(77);
+        $gateway = $this->getLocationGateway();
+        $data = $gateway->getBasicNodeData(77);
 
         self::assertLoadLocationProperties($data);
     }
@@ -80,8 +81,8 @@ public function testLoadLocation()
     public function testLoadLocationList()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $locationsData = $handler->getNodeDataList([77]);
+        $gateway = $this->getLocationGateway();
+        $locationsData = $gateway->getNodeDataList([77]);
 
         self::assertCount(1, $locationsData);
 
@@ -95,8 +96,8 @@ public function testLoadInvalidLocation()
         $this->expectException(\eZ\Publish\API\Repository\Exceptions\NotFoundException::class);
 
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->getBasicNodeData(1337);
+        $gateway = $this->getLocationGateway();
+        $gateway->getBasicNodeData(1337);
     }
 
     public function testLoadLocationDataByContent()
@@ -143,8 +144,8 @@ public function testLoadLocationDataByContentLimitSubtree()
     public function testMoveSubtreePathUpdate()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->moveSubtreeNodes(
+        $gateway = $this->getLocationGateway();
+        $gateway->moveSubtreeNodes(
             [
                 'path_string' => '/1/2/69/',
                 'path_identification_string' => 'products',
@@ -159,8 +160,7 @@ public function testMoveSubtreePathUpdate()
             ]
         );
 
-        /** @var $query \eZ\Publish\Core\Persistence\Database\SelectQuery */
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [65, '/1/2/', '', 1, 1, 0, 0],
@@ -170,9 +170,17 @@ public function testMoveSubtreePathUpdate()
                 [75, '/1/2/77/', 'solutions', 2, 2, 0, 0],
             ],
             $query
-                ->select('contentobject_id', 'path_string', 'path_identification_string', 'parent_node_id', 'depth', 'is_hidden', 'is_invisible')
+                ->select(
+                    'contentobject_id',
+                    'path_string',
+                    'path_identification_string',
+                    'parent_node_id',
+                    'depth',
+                    'is_hidden',
+                    'is_invisible'
+                )
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [69, 71, 75, 77, 2]))
+                ->where($query->expr()->in('node_id', [69, 71, 75, 77, 2]))
                 ->orderBy('contentobject_id')
         );
     }
@@ -180,9 +188,9 @@ public function testMoveSubtreePathUpdate()
     public function testMoveHiddenDestinationUpdate()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/77/');
-        $handler->moveSubtreeNodes(
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/77/');
+        $gateway->moveSubtreeNodes(
             [
                 'path_string' => '/1/2/69/',
                 'path_identification_string' => 'products',
@@ -197,8 +205,7 @@ public function testMoveHiddenDestinationUpdate()
             ]
         );
 
-        /** @var $query \eZ\Publish\Core\Persistence\Database\SelectQuery */
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [65, '/1/2/', '', 1, 1, 0, 0],
@@ -208,9 +215,17 @@ public function testMoveHiddenDestinationUpdate()
                 [75, '/1/2/77/', 'solutions', 2, 2, 1, 1],
             ],
             $query
-                ->select('contentobject_id', 'path_string', 'path_identification_string', 'parent_node_id', 'depth', 'is_hidden', 'is_invisible')
+                ->select(
+                    'contentobject_id',
+                    'path_string',
+                    'path_identification_string',
+                    'parent_node_id',
+                    'depth',
+                    'is_hidden',
+                    'is_invisible'
+                )
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [69, 71, 75, 77, 2]))
+                ->where($query->expr()->in('node_id', [69, 71, 75, 77, 2]))
                 ->orderBy('contentobject_id')
         );
     }
@@ -218,9 +233,9 @@ public function testMoveHiddenDestinationUpdate()
     public function testMoveHiddenSourceUpdate()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/');
-        $handler->moveSubtreeNodes(
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/');
+        $gateway->moveSubtreeNodes(
             [
                 'path_string' => '/1/2/69/',
                 'path_identification_string' => 'products',
@@ -235,8 +250,7 @@ public function testMoveHiddenSourceUpdate()
             ]
         );
 
-        /** @var $query \eZ\Publish\Core\Persistence\Database\SelectQuery */
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [65, '/1/2/', '', 1, 1, 0, 0],
@@ -246,9 +260,17 @@ public function testMoveHiddenSourceUpdate()
                 [75, '/1/2/77/', 'solutions', 2, 2, 0, 0],
             ],
             $query
-                ->select('contentobject_id', 'path_string', 'path_identification_string', 'parent_node_id', 'depth', 'is_hidden', 'is_invisible')
+                ->select(
+                    'contentobject_id',
+                    'path_string',
+                    'path_identification_string',
+                    'parent_node_id',
+                    'depth',
+                    'is_hidden',
+                    'is_invisible'
+                )
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [69, 71, 75, 77, 2]))
+                ->where($query->expr()->in('node_id', [69, 71, 75, 77, 2]))
                 ->orderBy('contentobject_id')
         );
     }
@@ -256,10 +278,10 @@ public function testMoveHiddenSourceUpdate()
     public function testMoveHiddenSourceChildUpdate()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/70/');
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/70/');
 
-        $handler->moveSubtreeNodes(
+        $gateway->moveSubtreeNodes(
             [
                 'path_string' => '/1/2/69/',
                 'path_identification_string' => 'products',
@@ -274,8 +296,7 @@ public function testMoveHiddenSourceChildUpdate()
             ]
         );
 
-        /** @var $query \eZ\Publish\Core\Persistence\Database\SelectQuery */
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [65, '/1/2/', '', 1, 1, 0, 0],
@@ -286,9 +307,17 @@ public function testMoveHiddenSourceChildUpdate()
                 [75, '/1/2/77/', 'solutions', 2, 2, 0, 0],
             ],
             $query
-                ->select('contentobject_id', 'path_string', 'path_identification_string', 'parent_node_id', 'depth', 'is_hidden', 'is_invisible')
+                ->select(
+                    'contentobject_id',
+                    'path_string',
+                    'path_identification_string',
+                    'parent_node_id',
+                    'depth',
+                    'is_hidden',
+                    'is_invisible'
+                )
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [69, 70, 71, 75, 77, 2]))
+                ->where($query->expr()->in('node_id', [69, 70, 71, 75, 77, 2]))
                 ->orderBy('contentobject_id')
         );
     }
@@ -299,10 +328,10 @@ public function testMoveHiddenSourceChildUpdate()
     public function testMoveSubtreeAssignmentUpdate()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->updateNodeAssignment(67, 2, 77, 5);
+        $gateway = $this->getLocationGateway();
+        $gateway->updateNodeAssignment(67, 2, 77, 5);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [67, 1, 0, 53, 1, 5, 77, '9cec85d730eec7578190ee95ce5a36f5', 0, 2, 1, 0, 0],
@@ -326,18 +355,18 @@ public function testMoveSubtreeAssignmentUpdate()
                     ]
                 )
                 ->from('eznode_assignment')
-                ->where($query->expr->eq('contentobject_id', 67))
+                ->where($query->expr()->eq('contentobject_id', 67))
         );
     }
 
     public function testUpdateSubtreeModificationTime()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
+        $gateway = $this->getLocationGateway();
         $time = time();
-        $handler->updateSubtreeModificationTime('/1/2/69/');
+        $gateway->updateSubtreeModificationTime('/1/2/69/');
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 ['/1/'],
@@ -347,7 +376,7 @@ public function testUpdateSubtreeModificationTime()
             $query
                 ->select('path_string')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->gte('modified_subnode', $time))
+                ->where($query->expr()->gte('modified_subnode', $time))
                 ->orderBy('path_string')
         );
     }
@@ -355,10 +384,10 @@ public function testUpdateSubtreeModificationTime()
     public function testHideUpdateHidden()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/');
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/');
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [1, 0, 0],
@@ -369,7 +398,7 @@ public function testHideUpdateHidden()
             $query
                 ->select('node_id', 'is_hidden', 'is_invisible')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [1, 2, 69, 75]))
+                ->where($query->expr()->in('node_id', [1, 2, 69, 75]))
                 ->orderBy('node_id')
         );
     }
@@ -380,11 +409,11 @@ public function testHideUpdateHidden()
     public function testHideUnhideUpdateHidden()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/');
-        $handler->unhideSubtree('/1/2/69/');
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/');
+        $gateway->unhideSubtree('/1/2/69/');
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [1, 0, 0],
@@ -395,7 +424,7 @@ public function testHideUnhideUpdateHidden()
             $query
                 ->select('node_id', 'is_hidden', 'is_invisible')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [1, 2, 69, 75]))
+                ->where($query->expr()->in('node_id', [1, 2, 69, 75]))
                 ->orderBy('node_id')
         );
     }
@@ -406,12 +435,12 @@ public function testHideUnhideUpdateHidden()
     public function testHideUnhideParentTree()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/');
-        $handler->hideSubtree('/1/2/69/70/');
-        $handler->unhideSubtree('/1/2/69/');
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/');
+        $gateway->hideSubtree('/1/2/69/70/');
+        $gateway->unhideSubtree('/1/2/69/');
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [1, 0, 0],
@@ -424,7 +453,7 @@ public function testHideUnhideParentTree()
             $query
                 ->select('node_id', 'is_hidden', 'is_invisible')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [1, 2, 69, 70, 71, 75]))
+                ->where($query->expr()->in('node_id', [1, 2, 69, 70, 71, 75]))
                 ->orderBy('node_id')
         );
     }
@@ -435,12 +464,12 @@ public function testHideUnhideParentTree()
     public function testHideUnhidePartialSubtree()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->hideSubtree('/1/2/69/');
-        $handler->hideSubtree('/1/2/69/70/');
-        $handler->unhideSubtree('/1/2/69/70/');
+        $gateway = $this->getLocationGateway();
+        $gateway->hideSubtree('/1/2/69/');
+        $gateway->hideSubtree('/1/2/69/70/');
+        $gateway->unhideSubtree('/1/2/69/70/');
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [1, 0, 0],
@@ -453,7 +482,7 @@ public function testHideUnhidePartialSubtree()
             $query
                 ->select('node_id', 'is_hidden', 'is_invisible')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [1, 2, 69, 70, 71, 75]))
+                ->where($query->expr()->in('node_id', [1, 2, 69, 70, 71, 75]))
                 ->orderBy('node_id')
         );
     }
@@ -461,10 +490,10 @@ public function testHideUnhidePartialSubtree()
     public function testSwapLocations()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->swap(70, 78);
+        $gateway = $this->getLocationGateway();
+        $gateway->swap(70, 78);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [70, 76],
@@ -473,7 +502,7 @@ public function testSwapLocations()
             $query
                 ->select('node_id', 'contentobject_id')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [70, 78]))
+                ->where($query->expr()->in('node_id', [70, 78]))
                 ->orderBy('node_id')
         );
     }
@@ -481,8 +510,8 @@ public function testSwapLocations()
     public function testCreateLocation()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->create(
+        $gateway = $this->getLocationGateway();
+        $gateway->create(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -496,7 +525,7 @@ public function testCreateLocation()
             ]
         );
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [70, '/1/2/69/70/'],
@@ -506,19 +535,18 @@ public function testCreateLocation()
             $query
                 ->select('node_id', 'path_string')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('contentobject_id', [68, 75]))
+                ->where($query->expr()->in('contentobject_id', [68, 75]))
                 ->orderBy('node_id')
         );
     }
 
     /**
-     * @covers \eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase::getMainNodeId
+     * @covers  \eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase::getMainNodeId
      * @depends testCreateLocation
      */
     public function testGetMainNodeId()
     {
-        // $this->insertDatabaseFixture( __DIR__ . '/_fixtures/full_example_tree.php' );
-        $handler = $this->getLocationGateway();
+        $gateway = $this->getLocationGateway();
 
         $parentLocationData = [
             'node_id' => '77',
@@ -527,7 +555,7 @@ public function testGetMainNodeId()
         ];
 
         // main location
-        $mainLocation = $handler->create(
+        $mainLocation = $gateway->create(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -540,7 +568,7 @@ public function testGetMainNodeId()
         );
 
         // secondary location
-        $handler->create(
+        $gateway->create(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -552,10 +580,10 @@ public function testGetMainNodeId()
             $parentLocationData
         );
 
-        $handlerReflection = new \ReflectionObject($handler);
-        $methodReflection = $handlerReflection->getMethod('getMainNodeId');
+        $gatewayReflection = new \ReflectionObject($gateway);
+        $methodReflection = $gatewayReflection->getMethod('getMainNodeId');
         $methodReflection->setAccessible(true);
-        self::assertEquals($mainLocation->id, $res = $methodReflection->invoke($handler, 68));
+        self::assertEquals($mainLocation->id, $res = $methodReflection->invoke($gateway, 68));
     }
 
     public static function getCreateLocationValues()
@@ -578,7 +606,7 @@ public static function getCreateLocationValues()
     }
 
     /**
-     * @depends testCreateLocation
+     * @depends      testCreateLocation
      * @dataProvider getCreateLocationValues
      */
     public function testCreateLocationValues($field, $value)
@@ -588,8 +616,8 @@ public function testCreateLocationValues($field, $value)
         }
 
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->create(
+        $gateway = $this->getLocationGateway();
+        $gateway->create(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -608,13 +636,13 @@ public function testCreateLocationValues($field, $value)
             ]
         );
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[$value]],
             $query
                 ->select($field)
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->eq('node_id', 228))
+                ->where($query->expr()->eq('node_id', 228))
         );
     }
 
@@ -637,7 +665,7 @@ public static function getCreateLocationReturnValues()
     }
 
     /**
-     * @depends testCreateLocation
+     * @depends      testCreateLocation
      * @dataProvider getCreateLocationReturnValues
      */
     public function testCreateLocationReturnValues($field, $value)
@@ -647,8 +675,8 @@ public function testCreateLocationReturnValues($field, $value)
         }
 
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $location = $handler->create(
+        $gateway = $this->getLocationGateway();
+        $location = $gateway->create(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -687,8 +715,8 @@ public static function getUpdateLocationData()
     public function testUpdateLocation($field, $value)
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->update(
+        $gateway = $this->getLocationGateway();
+        $gateway->update(
             new Location\UpdateStruct(
                 [
                     'priority' => 23,
@@ -700,44 +728,103 @@ public function testUpdateLocation($field, $value)
             70
         );
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[$value]],
             $query
                 ->select($field)
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [70]))
+                ->where($query->expr()->in('node_id', [70]))
         );
     }
 
     public static function getNodeAssignmentValues()
     {
         return [
-            ['contentobject_version', 1],
-            ['from_node_id', 0],
-            ['id', 215],
-            ['is_main', 0],
-            ['op_code', 3],
-            ['parent_node', 77],
-            ['parent_remote_id', 'some_id'],
-            ['remote_id', '0'],
-            ['sort_field', 2],
-            ['sort_order', 0],
-            ['is_main', 0],
-            ['priority', 1],
-            ['is_hidden', 1],
+            ['contentobject_version', [1]],
+            ['from_node_id', [0]],
+            ['id', [215]],
+            ['is_main', [0]],
+            ['op_code', [3]],
+            ['parent_node', [77]],
+            ['parent_remote_id', ['some_id']],
+            ['remote_id', ['0']],
+            ['sort_field', [2]],
+            ['sort_order', [0]],
+            ['is_main', [0]],
+            ['priority', [1]],
+            ['is_hidden', [1]],
         ];
     }
 
+    private function buildGenericNodeSelectContentWithParentQuery(
+        int $contentId,
+        int $parentLocationId,
+        string $nodeTable,
+        string $parentNodeIdColumnName,
+        array $fields
+    ): QueryBuilder {
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
+        $expr = $query->expr();
+        $query
+            ->select($fields)
+            ->from($nodeTable)
+            ->where(
+                $expr->eq(
+                    'contentobject_id',
+                    $query->createPositionalParameter($contentId, ParameterType::INTEGER)
+                )
+            )
+            ->andWhere(
+                $expr->eq(
+                    $parentNodeIdColumnName,
+                    $query->createPositionalParameter($parentLocationId, ParameterType::INTEGER)
+                )
+            );
+
+        return $query;
+    }
+
+    private function buildNodeAssignmentSelectContentWithParentQuery(
+        int $contentId,
+        int $parentLocationId,
+        array $fields
+    ): QueryBuilder {
+        return $this->buildGenericNodeSelectContentWithParentQuery(
+            $contentId,
+            $parentLocationId,
+            'eznode_assignment',
+            'parent_node',
+            $fields
+        );
+    }
+
+    private function buildContentTreeSelectContentWithParentQuery(
+        int $contentId,
+        int $parentLocationId,
+        array $fields
+    ): QueryBuilder {
+        return $this->buildGenericNodeSelectContentWithParentQuery(
+            $contentId,
+            $parentLocationId,
+            Gateway::CONTENT_TREE_TABLE,
+            'parent_node_id',
+            $fields
+        );
+    }
+
     /**
-     * @depends testCreateLocation
+     * @depends      testCreateLocation
      * @dataProvider getNodeAssignmentValues
+     *
+     * @param string $field
+     * @param array $expectedResult
      */
-    public function testCreateLocationNodeAssignmentCreation($field, $value)
+    public function testCreateLocationNodeAssignmentCreation(string $field, array $expectedResult)
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -750,22 +837,13 @@ public function testCreateLocationNodeAssignmentCreation($field, $value)
                     'hidden' => 1,
                 ]
             ),
-            '77',
+            77,
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
-            [[$value]],
-            $query
-                ->select($field)
-                ->from('eznode_assignment')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node', 77)
-                    )
-                )
+            [$expectedResult],
+            $this->buildNodeAssignmentSelectContentWithParentQuery(68, 77, [$field])
         );
     }
 
@@ -775,8 +853,8 @@ public function testCreateLocationNodeAssignmentCreation($field, $value)
     public function testCreateLocationNodeAssignmentCreationMainLocation()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -792,18 +870,9 @@ public function testCreateLocationNodeAssignmentCreationMainLocation()
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
             [[1]],
-            $query
-                ->select('is_main')
-                ->from('eznode_assignment')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node', 77)
-                    )
-                )
+            $this->buildNodeAssignmentSelectContentWithParentQuery(68, 77, ['is_main'])
         );
     }
 
@@ -832,7 +901,7 @@ public function testUpdateLocationsContentVersionNo()
 
         $gateway->updateLocationsContentVersionNo(4096, 2);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [2],
@@ -842,7 +911,7 @@ public function testUpdateLocationsContentVersionNo()
             )->from(
                 'ezcontentobject_tree'
             )->where(
-                $query->expr->eq(
+                $query->expr()->eq(
                     'contentobject_id',
                     4096
                 )
@@ -856,20 +925,18 @@ public function testUpdateLocationsContentVersionNo()
     public function testDeleteNodeAssignment()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
+        $gateway = $this->getLocationGateway();
 
-        $handler->deleteNodeAssignment(11);
+        $gateway->deleteNodeAssignment(11);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[0]],
             $query
                 ->select('count(*)')
                 ->from('eznode_assignment')
                 ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 11)
-                    )
+                    $query->expr()->eq('contentobject_id', 11)
                 )
         );
     }
@@ -880,33 +947,28 @@ public function testDeleteNodeAssignment()
     public function testDeleteNodeAssignmentWithSecondArgument()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
-        $handler = $this->getLocationGateway();
+        $gateway = $this->getLocationGateway();
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $query
             ->select('count(*)')
             ->from('eznode_assignment')
             ->where(
-                $query->expr->lAnd(
-                    $query->expr->eq('contentobject_id', 11)
-                )
+                $query->expr()->eq('contentobject_id', 11)
             );
-        $statement = $query->prepare();
-        $statement->execute();
+        $statement = $query->execute();
         $nodeAssignmentsCount = (int)$statement->fetchColumn();
 
-        $handler->deleteNodeAssignment(11, 1);
+        $gateway->deleteNodeAssignment(11, 1);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[$nodeAssignmentsCount - 1]],
             $query
                 ->select('count(*)')
                 ->from('eznode_assignment')
                 ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 11)
-                    )
+                    $query->expr()->eq('contentobject_id', 11)
                 )
         );
     }
@@ -934,15 +996,15 @@ public static function getConvertNodeAssignmentsLocationValues()
     }
 
     /**
-     * @depends testCreateLocationNodeAssignmentCreation
+     * @depends      testCreateLocationNodeAssignmentCreation
      * @dataProvider getConvertNodeAssignmentsLocationValues
      */
     public function testConvertNodeAssignments($field, $value)
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -962,23 +1024,29 @@ public function testConvertNodeAssignments($field, $value)
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $handler->createLocationsFromNodeAssignments(68, 1);
+        $gateway->createLocationsFromNodeAssignments(68, 1);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
+        $expr = $query->expr();
         $query
             ->select($field)
-            ->from('ezcontentobject_tree')
+            ->from(Gateway::CONTENT_TREE_TABLE)
             ->where(
-                $query->expr->lAnd(
-                    $query->expr->eq('contentobject_id', 68),
-                    $query->expr->eq('parent_node_id', 77)
+                $expr->eq(
+                    'contentobject_id',
+                    $query->createPositionalParameter(68, ParameterType::INTEGER)
+                )
+            )
+            ->andWhere(
+                $expr->eq(
+                    'parent_node_id',
+                    $query->createPositionalParameter(77, ParameterType::INTEGER)
                 )
             );
 
         if ($field === 'modified_subnode') {
-            $statement = $query->prepare();
-            $statement->execute();
-            $result = $statement->fetch(\PDO::FETCH_ASSOC);
+            $statement = $query->execute();
+            $result = $statement->fetch(FetchMode::ASSOCIATIVE);
             $this->assertGreaterThanOrEqual($value, $result);
         } else {
             $this->assertQueryResult(
@@ -995,8 +1063,8 @@ public function testConvertNodeAssignmentsMainLocation()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -1012,24 +1080,15 @@ public function testConvertNodeAssignmentsMainLocation()
                     'invisible' => false,
                 ]
             ),
-            '77',
+            77,
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $handler->createLocationsFromNodeAssignments(68, 1);
+        $gateway->createLocationsFromNodeAssignments(68, 1);
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
             [[228]],
-            $query
-                ->select('main_node_id')
-                ->from('ezcontentobject_tree')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node_id', 77)
-                    )
-                )
+            $this->buildContentTreeSelectContentWithParentQuery(68, 77, ['main_node_id'])
         );
     }
 
@@ -1040,8 +1099,8 @@ public function testConvertNodeAssignmentsParentHidden()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -1057,24 +1116,19 @@ public function testConvertNodeAssignmentsParentHidden()
                     'invisible' => false,
                 ]
             ),
-            '224',
+            224,
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $handler->createLocationsFromNodeAssignments(68, 1);
+        $gateway->createLocationsFromNodeAssignments(68, 1);
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
             [[0, 1]],
-            $query
-                ->select('is_hidden, is_invisible')
-                ->from('ezcontentobject_tree')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node_id', 224)
-                    )
-                )
+            $this->buildContentTreeSelectContentWithParentQuery(
+                68,
+                224,
+                ['is_hidden, is_invisible']
+            )
         );
     }
 
@@ -1085,8 +1139,8 @@ public function testConvertNodeAssignmentsParentInvisible()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -1102,24 +1156,19 @@ public function testConvertNodeAssignmentsParentInvisible()
                     'invisible' => false,
                 ]
             ),
-            '225',
+            225,
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $handler->createLocationsFromNodeAssignments(68, 1);
+        $gateway->createLocationsFromNodeAssignments(68, 1);
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
             [[0, 1]],
-            $query
-                ->select('is_hidden, is_invisible')
-                ->from('ezcontentobject_tree')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node_id', 225)
-                    )
-                )
+            $this->buildContentTreeSelectContentWithParentQuery(
+                68,
+                225,
+                ['is_hidden, is_invisible']
+            )
         );
     }
 
@@ -1130,8 +1179,8 @@ public function testConvertNodeAssignmentsUpdateAssignment()
     {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
-        $handler = $this->getLocationGateway();
-        $handler->createNodeAssignment(
+        $gateway = $this->getLocationGateway();
+        $gateway->createNodeAssignment(
             new CreateStruct(
                 [
                     'contentId' => 68,
@@ -1147,20 +1196,11 @@ public function testConvertNodeAssignmentsUpdateAssignment()
             DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE
         );
 
-        $handler->createLocationsFromNodeAssignments(68, 1);
+        $gateway->createLocationsFromNodeAssignments(68, 1);
 
-        $query = $this->handler->createSelectQuery();
         $this->assertQueryResult(
             [[DoctrineDatabase::NODE_ASSIGNMENT_OP_CODE_CREATE_NOP]],
-            $query
-                ->select('op_code')
-                ->from('eznode_assignment')
-                ->where(
-                    $query->expr->lAnd(
-                        $query->expr->eq('contentobject_id', 68),
-                        $query->expr->eq('parent_node', 77)
-                    )
-                )
+            $this->buildNodeAssignmentSelectContentWithParentQuery(68, 77, ['op_code'])
         );
     }
 
@@ -1172,16 +1212,16 @@ public function testConvertNodeAssignmentsUpdateAssignment()
     public function testSetSectionForSubtree()
     {
         $this->insertDatabaseFixture(__DIR__ . '/../../_fixtures/contentobjects.php');
-        $handler = $this->getLocationGateway();
-        $handler->setSectionForSubtree('/1/2/69/70/', 23);
+        $gateway = $this->getLocationGateway();
+        $gateway->setSectionForSubtree('/1/2/69/70/', 23);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[68], [69]],
             $query
                 ->select('id')
                 ->from('ezcontentobject')
-                ->where($query->expr->eq('section_id', 23))
+                ->where($query->expr()->eq('section_id', 23))
         );
     }
 
@@ -1202,13 +1242,28 @@ public function testChangeMainLocation()
             ->insert('ezcontentobject_tree')
             ->values(
                 [
-                    'contentobject_id' => $query->createPositionalParameter(10, ParameterType::INTEGER),
-                    'contentobject_version' => $query->createPositionalParameter(2, ParameterType::INTEGER),
+                    'contentobject_id' => $query->createPositionalParameter(
+                        10,
+                        ParameterType::INTEGER
+                    ),
+                    'contentobject_version' => $query->createPositionalParameter(
+                        2,
+                        ParameterType::INTEGER
+                    ),
                     'main_node_id' => $query->createPositionalParameter(15, ParameterType::INTEGER),
                     'node_id' => $query->createPositionalParameter(228, ParameterType::INTEGER),
-                    'parent_node_id' => $query->createPositionalParameter(227, ParameterType::INTEGER),
-                    'path_string' => $query->createPositionalParameter('/1/5/13/228/', ParameterType::STRING),
-                    'remote_id' => $query->createPositionalParameter('asdfg123437', ParameterType::STRING),
+                    'parent_node_id' => $query->createPositionalParameter(
+                        227,
+                        ParameterType::INTEGER
+                    ),
+                    'path_string' => $query->createPositionalParameter(
+                        '/1/5/13/228/',
+                        ParameterType::STRING
+                    ),
+                    'remote_id' => $query->createPositionalParameter(
+                        'asdfg123437',
+                        ParameterType::STRING
+                    ),
                 ]
             );
         $query->execute();
@@ -1218,12 +1273,21 @@ public function testChangeMainLocation()
             ->insert('eznode_assignment')
             ->values(
                 [
-                    'contentobject_id' => $query->createPositionalParameter(10, ParameterType::INTEGER),
-                    'contentobject_version' => $query->createPositionalParameter(2, ParameterType::INTEGER),
+                    'contentobject_id' => $query->createPositionalParameter(
+                        10,
+                        ParameterType::INTEGER
+                    ),
+                    'contentobject_version' => $query->createPositionalParameter(
+                        2,
+                        ParameterType::INTEGER
+                    ),
                     'id' => $query->createPositionalParameter(0, ParameterType::INTEGER),
                     'is_main' => $query->createPositionalParameter(0, ParameterType::INTEGER),
                     'parent_node' => $query->createPositionalParameter(227, ParameterType::INTEGER),
-                    'parent_remote_id' => $query->createPositionalParameter('5238a276bf8231fbcf8a986cdc82a6a5', ParameterType::STRING),
+                    'parent_remote_id' => $query->createPositionalParameter(
+                        '5238a276bf8231fbcf8a986cdc82a6a5',
+                        ParameterType::STRING
+                    ),
                 ]
             );
         $query->execute();
@@ -1258,12 +1322,21 @@ public function testChangeMainLocation()
                 ->select('is_main')
                 ->from('eznode_assignment')
                 ->where(
-                $query->expr()->andX(
-                    $query->expr()->eq('contentobject_id', $query->createPositionalParameter(10, ParameterType::INTEGER)),
-                    $query->expr()->eq('contentobject_version', $query->createPositionalParameter(2, ParameterType::INTEGER)),
-                    $query->expr()->eq('parent_node', $query->createPositionalParameter(227, ParameterType::INTEGER))
+                    $query->expr()->andX(
+                        $query->expr()->eq(
+                            'contentobject_id',
+                            $query->createPositionalParameter(10, ParameterType::INTEGER)
+                        ),
+                        $query->expr()->eq(
+                            'contentobject_version',
+                            $query->createPositionalParameter(2, ParameterType::INTEGER)
+                        ),
+                        $query->expr()->eq(
+                            'parent_node',
+                            $query->createPositionalParameter(227, ParameterType::INTEGER)
+                        )
+                    )
                 )
-            )
         );
 
         $query = $connection->createQueryBuilder();
@@ -1274,9 +1347,18 @@ public function testChangeMainLocation()
                 ->from('eznode_assignment')
                 ->where(
                     $query->expr()->andX(
-                        $query->expr()->eq('contentobject_id', $query->createPositionalParameter(10, ParameterType::INTEGER)),
-                        $query->expr()->eq('contentobject_version', $query->createPositionalParameter(2, ParameterType::INTEGER)),
-                        $query->expr()->eq('parent_node', $query->createPositionalParameter(44, ParameterType::INTEGER))
+                        $query->expr()->eq(
+                            'contentobject_id',
+                            $query->createPositionalParameter(10, ParameterType::INTEGER)
+                        ),
+                        $query->expr()->eq(
+                            'contentobject_version',
+                            $query->createPositionalParameter(2, ParameterType::INTEGER)
+                        ),
+                        $query->expr()->eq(
+                            'parent_node',
+                            $query->createPositionalParameter(44, ParameterType::INTEGER)
+                        )
                     )
                 )
         );
@@ -1318,13 +1400,28 @@ public function testGetFallbackMainNodeData(): void
             ->insert('ezcontentobject_tree')
             ->values(
                 [
-                    'contentobject_id' => $query->createPositionalParameter(12, ParameterType::INTEGER),
-                    'contentobject_version' => $query->createPositionalParameter(1, ParameterType::INTEGER),
+                    'contentobject_id' => $query->createPositionalParameter(
+                        12,
+                        ParameterType::INTEGER
+                    ),
+                    'contentobject_version' => $query->createPositionalParameter(
+                        1,
+                        ParameterType::INTEGER
+                    ),
                     'main_node_id' => $query->createPositionalParameter(13, ParameterType::INTEGER),
                     'node_id' => $query->createPositionalParameter(228, ParameterType::INTEGER),
-                    'parent_node_id' => $query->createPositionalParameter(227, ParameterType::INTEGER),
-                    'path_string' => $query->createPositionalParameter('/1/5/13/228/', ParameterType::STRING),
-                    'remote_id' => $query->createPositionalParameter('asdfg123437', ParameterType::STRING),
+                    'parent_node_id' => $query->createPositionalParameter(
+                        227,
+                        ParameterType::INTEGER
+                    ),
+                    'path_string' => $query->createPositionalParameter(
+                        '/1/5/13/228/',
+                        ParameterType::STRING
+                    ),
+                    'remote_id' => $query->createPositionalParameter(
+                        'asdfg123437',
+                        ParameterType::STRING
+                    ),
                 ]
             );
         $query->execute();
@@ -1368,17 +1465,21 @@ public function providerForTestUpdatePathIdentificationString()
     /**
      * Test for the updatePathIdentificationString() method.
      *
-     * @covers \eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase::updatePathIdentificationString
+     * @covers       \eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase::updatePathIdentificationString
      * @dataProvider providerForTestUpdatePathIdentificationString
      */
-    public function testUpdatePathIdentificationString($locationId, $parentLocationId, $text, $expected)
-    {
+    public function testUpdatePathIdentificationString(
+        $locationId,
+        $parentLocationId,
+        $text,
+        $expected
+    ) {
         $this->insertDatabaseFixture(__DIR__ . '/_fixtures/full_example_tree.php');
 
         $gateway = $this->getLocationGateway();
         $gateway->updatePathIdentificationString($locationId, $parentLocationId, $text);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[$expected]],
             $query->select(
@@ -1386,7 +1487,7 @@ public function testUpdatePathIdentificationString($locationId, $parentLocationI
             )->from(
                 'ezcontentobject_tree'
             )->where(
-                $query->expr->eq('node_id', $locationId)
+                $query->expr()->eq('node_id', $locationId)
             )
         );
     }
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTrashTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTrashTest.php
index 8ff3212ee9..3569217fb1 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTrashTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Location/Gateway/DoctrineDatabaseTrashTest.php
@@ -1,13 +1,12 @@
 <?php
 
 /**
- * File contains: eZ\Publish\Core\Persistence\Legacy\Tests\Content\Location\Gateway\DoctrineDatabaseTest class.
- *
  * @copyright Copyright (C) eZ Systems AS. All rights reserved.
  * @license For full copyright and license information view LICENSE file distributed with this source code.
  */
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\Content\Location\Gateway;
 
+use Doctrine\DBAL\ParameterType;
 use eZ\Publish\Core\Persistence\Legacy\Tests\Content\LanguageAwareTestCase;
 use eZ\Publish\Core\Persistence\Legacy\Content\Location\Gateway\DoctrineDatabase;
 use eZ\Publish\API\Repository\Values\Content\Query\SortClause;
@@ -37,7 +36,7 @@ public function testTrashLocation()
         $handler = $this->getLocationGateway();
         $handler->trashLocation(71);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [1, 0],
@@ -48,7 +47,7 @@ public function testTrashLocation()
             $query
                 ->select('node_id', 'priority')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('node_id', [1, 2, 69, 70, 71]))
+                ->where($query->expr()->in('node_id', [1, 2, 69, 70, 71]))
         );
     }
 
@@ -61,7 +60,7 @@ public function testTrashLocationUpdateTrashTable()
         $handler = $this->getLocationGateway();
         $handler->trashLocation(71);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [
                 [71, '/1/2/69/70/71/'],
@@ -104,13 +103,13 @@ public function testUntrashLocationDefault($property, $value)
 
         $handler->untrashLocation(71);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [[$value]],
             $query
                 ->select($property)
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('contentobject_id', [69]))
+                ->where($query->expr()->in('contentobject_id', [69]))
         );
     }
 
@@ -125,13 +124,13 @@ public function testUntrashLocationNewParent()
 
         $handler->untrashLocation(71, 1);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [['228', '1', '/1/228/']],
             $query
                 ->select('node_id', 'parent_node_id', 'path_string')
                 ->from('ezcontentobject_tree')
-                ->where($query->expr->in('contentobject_id', [69]))
+                ->where($query->expr()->in('contentobject_id', [69]))
         );
     }
 
@@ -411,7 +410,7 @@ public function testCleanupTrash()
         $this->trashSubtree();
         $handler->cleanupTrash();
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [],
             $query
@@ -430,13 +429,13 @@ public function testRemoveElementFromTrash()
         $this->trashSubtree();
         $handler->removeElementFromTrash(71);
 
-        $query = $this->handler->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $this->assertQueryResult(
             [],
             $query
                 ->select('*')
                 ->from('ezcontentobject_trash')
-                ->where($query->expr->eq('node_id', 71))
+                ->where($query->expr()->eq('node_id', 71))
         );
     }
 
@@ -452,15 +451,34 @@ public function testCountLocationsByContentId()
         self::assertSame(1, $handler->countLocationsByContentId(67));
 
         // Insert a new node and count again
-        $query = $this->handler->createInsertQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
         $query
-            ->insertInto('ezcontentobject_tree')
-            ->set('contentobject_id', $query->bindValue(67, null, \PDO::PARAM_INT))
-            ->set('contentobject_version', $query->bindValue(1, null, \PDO::PARAM_INT))
-            ->set('path_string', $query->bindValue('/1/2/96'))
-            ->set('parent_node_id', $query->bindValue(96, null, \PDO::PARAM_INT))
-            ->set('remote_id', $query->bindValue('some_remote_id'));
-        $query->prepare()->execute();
+            ->insert('ezcontentobject_tree')
+            ->values(
+                [
+                    'contentobject_id' => $query->createPositionalParameter(
+                        67,
+                        ParameterType::INTEGER
+                    ),
+                    'contentobject_version' => $query->createPositionalParameter(
+                        1,
+                        ParameterType::INTEGER
+                    ),
+                    'path_string' => $query->createPositionalParameter(
+                        '/1/2/96',
+                        ParameterType::INTEGER
+                    ),
+                    'parent_node_id' => $query->createPositionalParameter(
+                        96,
+                        ParameterType::INTEGER
+                    ),
+                    'remote_id' => $query->createPositionalParameter(
+                        'some_remote_id',
+                        ParameterType::STRING
+                    ),
+                ]
+            );
+        $query->execute();
         self::assertSame(2, $handler->countLocationsByContentId(67));
     }
 }
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/ObjectState/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/ObjectState/Gateway/DoctrineDatabaseTest.php
index 75a9d46785..20d82b72fd 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/ObjectState/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/ObjectState/Gateway/DoctrineDatabaseTest.php
@@ -1,8 +1,6 @@
 <?php
 
 /**
- * File contains: eZ\Publish\Core\Persistence\Legacy\Tests\Content\ObjectState\Gateway\DoctrineDatabaseTest class.
- *
  * @copyright Copyright (C) eZ Systems AS. All rights reserved.
  * @license For full copyright and license information view LICENSE file distributed with this source code.
  */
@@ -346,34 +344,8 @@ public function testUpdateObjectStateLinks()
 
         $gateway->updateObjectStateLinks(1, 2);
 
-        $query = $this->getDatabaseHandler()->createSelectQuery();
-        $query
-        ->select($query->expr->count('*'))
-        ->from('ezcobj_state_link')
-        ->where('contentobject_state_id = 1');
-
-        $statement = $query->prepare();
-        $statement->execute();
-
-        $this->assertEquals(
-            0,
-            $statement->fetchColumn()
-        );
-
-        $query = $this->getDatabaseHandler()->createSelectQuery();
-        $query
-        ->select($query->expr->count('*'))
-        ->from('ezcobj_state_link')
-        ->where('contentobject_state_id = 2');
-
-        $statement = $query->prepare();
-        $statement->execute();
-
-        $this->assertEquals(
-            // The number of objects in the fixtures
-            185,
-            $statement->fetchColumn()
-        );
+        self::assertSame(0, $gateway->getContentCount(1));
+        self::assertSame(185, $gateway->getContentCount(2));
     }
 
     /**
@@ -385,19 +357,7 @@ public function testDeleteObjectStateLinks()
 
         $gateway->deleteObjectStateLinks(1);
 
-        $query = $this->getDatabaseHandler()->createSelectQuery();
-        $query
-            ->select($query->expr->count('*'))
-            ->from('ezcobj_state_link')
-            ->where('contentobject_state_id = 1');
-
-        $statement = $query->prepare();
-        $statement->execute();
-
-        $this->assertEquals(
-            0,
-            $statement->fetchColumn()
-        );
+        self::assertSame(0, $gateway->getContentCount(1));
     }
 
     /**
@@ -488,7 +448,7 @@ public function testSetContentState()
                     'contentobject_state_id' => 2,
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('contentobject_id', 'contentobject_state_id')
                 ->from('ezcobj_state_link')
                 ->where('contentobject_id = 42')
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Section/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Section/Gateway/DoctrineDatabaseTest.php
index 07915b74cc..3dfb0d0b39 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Section/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Section/Gateway/DoctrineDatabaseTest.php
@@ -42,7 +42,7 @@ public function testInsertSection()
         $gateway = $this->getDatabaseGateway();
 
         $gateway->insertSection('New Section', 'new_section');
-        $query = $this->getDatabaseHandler()->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
 
         $this->assertQueryResult(
             [
@@ -56,7 +56,12 @@ public function testInsertSection()
             $query
                 ->select('id', 'identifier', 'name', 'locale')
                 ->from('ezsection')
-                ->where($query->expr->eq('identifier', $query->bindValue('new_section')))
+                ->where(
+                    $query->expr()->eq(
+                        'identifier',
+                        $query->createPositionalParameter('new_section')
+                    )
+                )
         );
     }
 
@@ -78,7 +83,7 @@ public function testUpdateSection()
                     'locale' => '',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('id', 'identifier', 'name', 'locale')
                 ->from('ezsection')
                 ->where('id=2')
@@ -224,7 +229,7 @@ public function testDeleteSection()
     {
         $gateway = $this->getDatabaseGateway();
 
-        $result = $gateway->deleteSection(2);
+        $gateway->deleteSection(2);
 
         $this->assertQueryResult(
             [
@@ -232,7 +237,7 @@ public function testDeleteSection()
                     'count' => '5',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * ) AS count')
                 ->from('ezsection')
         );
@@ -243,7 +248,7 @@ public function testDeleteSection()
                     'count' => '0',
                 ],
             ],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * ) AS count')
                 ->from('ezsection')
                 ->where('id=2')
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Type/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Type/Gateway/DoctrineDatabaseTest.php
index 74026f2947..66e394ae85 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Type/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/Type/Gateway/DoctrineDatabaseTest.php
@@ -57,8 +57,7 @@ public function testInsertGroup()
                     'name' => 'Media',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'id',
                     'created',
@@ -116,13 +115,12 @@ public function testUpdateGroup()
             [
                 ['3'],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT(*)')
                 ->from('ezcontentclassgroup')
         );
 
-        $q = $this->getDatabaseHandler()->createSelectQuery();
+        $q = $this->getDatabaseConnection()->createQueryBuilder();
         $q
             ->select(
                 'id',
@@ -250,8 +248,7 @@ public function testDeleteGroup()
                 ['1'],
                 ['3'],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('id')
                 ->from('ezcontentclassgroup')
         );
@@ -485,8 +482,7 @@ public function testInsertType($column, $expectation)
 
         $this->assertQueryResult(
             [[$expectation]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select($column)
                 ->from('ezcontentclass'),
             'Inserted Type data incorrect in column ' . $column
@@ -527,8 +523,7 @@ function ($value) {
                 },
                 $expectation
             ),
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select($column)
                 ->from('ezcontentclass_name'),
             'Inserted Type data incorrect in column ' . $column
@@ -618,8 +613,7 @@ public function testInsertFieldDefinition()
                     'serialized_data_text' => 'a:2:{i:0;s:3:"foo";i:1;s:3:"bar";}',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'contentclass_id',
                     'serialized_name_list',
@@ -732,8 +726,7 @@ public function testDeleteFieldDefinition()
 
         $this->assertQueryResult(
             [[5]],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT(*)')
                 ->from('ezcontentclass_attribute')
         );
@@ -784,8 +777,7 @@ public function testUpdateFieldDefinition()
                     'serialized_data_text' => 'a:2:{i:0;s:3:"foo";i:1;s:3:"bar";}',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'category',
                     'contentclass_id',
@@ -839,8 +831,7 @@ public function testInsertGroupAssignment()
                     'group_name' => 'Media',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'contentclass_id',
                     'contentclass_version',
@@ -865,8 +856,7 @@ public function testDeleteGroupAssignment()
 
         $this->assertQueryResult(
             [['1']],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     'COUNT(*)'
                 )->from('ezcontentclass_classgroup')
@@ -896,8 +886,7 @@ public function testUpdateType($fieldName, $expectedValue)
                     $fieldName => $expectedValue,
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select(
                     $fieldName
                 )->from('ezcontentclass')
@@ -940,8 +929,7 @@ public function testUpdateTypeName()
                     'name' => 'New Folder for you',
                 ],
             ],
-            $this->getDatabaseHandler()
-                ->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('*')
                 ->from('ezcontentclass_name')
                 ->where('contentclass_id = 1 AND contentclass_version = 0')
@@ -1058,13 +1046,12 @@ public function testDeleteFieldDefinitionsForTypeExisting()
 
         $gateway->deleteFieldDefinitionsForType(1, 0);
 
-        $countAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countAffectedAttr
             ->select('COUNT(*)')
             ->from('ezcontentclass_attribute')
             ->where(
-                $countAffectedAttr->expr->eq(
+                $countAffectedAttr->expr()->eq(
                     'contentclass_id',
                     1
                 )
@@ -1075,8 +1062,7 @@ public function testDeleteFieldDefinitionsForTypeExisting()
             $countAffectedAttr
         );
 
-        $countNotAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countNotAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countNotAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass_attribute');
 
@@ -1099,8 +1085,7 @@ public function testDeleteFieldDefinitionsForTypeNotExisting()
 
         $gateway->deleteFieldDefinitionsForType(23, 1);
 
-        $countNotAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countNotAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countNotAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass_attribute');
 
@@ -1123,8 +1108,7 @@ public function testDeleteGroupAssignmentsForTypeExisting()
 
         $gateway->deleteGroupAssignmentsForType(1, 0);
 
-        $countAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass_classgroup');
 
@@ -1147,8 +1131,7 @@ public function testDeleteGroupAssignmentsForTypeNotExisting()
 
         $gateway->deleteType(23, 1);
 
-        $countAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass_classgroup');
 
@@ -1171,8 +1154,7 @@ public function testDeleteTypeExisting()
 
         $gateway->deleteType(1, 0);
 
-        $countAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass');
 
@@ -1195,8 +1177,7 @@ public function testDeleteTypeNotExisting()
 
         $gateway->deleteType(23, 1);
 
-        $countAffectedAttr = $this->getDatabaseHandler()
-            ->createSelectQuery();
+        $countAffectedAttr = $this->getDatabaseConnection()->createQueryBuilder();
         $countAffectedAttr->select('COUNT(*)')
             ->from('ezcontentclass');
 
@@ -1220,7 +1201,7 @@ public function testPublishTypeAndFields()
 
         $this->assertQueryResult(
             [[1]],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * )')
                 ->from('ezcontentclass')
                 ->where('id = 1 AND version = 0')
@@ -1228,7 +1209,7 @@ public function testPublishTypeAndFields()
 
         $this->assertQueryResult(
             [[2]],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * )')
                 ->from('ezcontentclass_classgroup')
                 ->where('contentclass_id = 1 AND contentclass_version = 0')
@@ -1236,7 +1217,7 @@ public function testPublishTypeAndFields()
 
         $this->assertQueryResult(
             [[3]],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * )')
                 ->from('ezcontentclass_attribute')
                 ->where('contentclass_id = 1 AND version = 0')
@@ -1244,7 +1225,7 @@ public function testPublishTypeAndFields()
 
         $this->assertQueryResult(
             [[1]],
-            $this->getDatabaseHandler()->createSelectQuery()
+            $this->getDatabaseConnection()->createQueryBuilder()
                 ->select('COUNT( * )')
                 ->from('ezcontentclass_name')
                 ->where('contentclass_id = 1 AND contentclass_version = 0')
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/UrlAlias/UrlAliasHandlerTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/UrlAlias/UrlAliasHandlerTest.php
index 07fc45cbb6..3d6926f08e 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Content/UrlAlias/UrlAliasHandlerTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Content/UrlAlias/UrlAliasHandlerTest.php
@@ -6,6 +6,7 @@
  */
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\Content;
 
+use eZ\Publish\API\Repository\Exceptions\InvalidArgumentException;
 use eZ\Publish\Core\Persistence\Legacy\Content\UrlAlias\Gateway as UrlAliasGateway;
 use eZ\Publish\Core\Persistence\Legacy\Tests\TestCase;
 use eZ\Publish\Core\Persistence\Legacy\Content\UrlAlias\Handler;
@@ -85,7 +86,7 @@ public function testLookupThrowsNotFoundException()
      */
     public function testLookupThrowsInvalidArgumentException()
     {
-        $this->expectException(\eZ\Publish\API\Repository\Exceptions\InvalidArgumentException::class);
+        $this->expectException(InvalidArgumentException::class);
 
         $handler = $this->getHandler();
         $handler->lookup(str_repeat('/1', 99));
@@ -5291,41 +5292,20 @@ public function testLocationSwappedMultipleLanguagesUpdatesLocationPathIdentific
         self::assertEquals('jedan', $locationData['path_identification_string']);
     }
 
-    /**
-     * @return int
-     */
-    protected function countRows()
+    protected function countRows(): int
     {
         /** @var \eZ\Publish\Core\Persistence\Database\SelectQuery $query */
-        $query = $this->getDatabaseHandler()->createSelectQuery();
-        $query->select(
-            $query->expr->count('*')
-        )->from(
-            $this->getDatabaseHandler()->quoteTable('ezurlalias_ml')
-        );
+        $connection = $this->getDatabaseConnection();
+        $query = $connection->createQueryBuilder();
+        $query
+            ->select($connection->getDatabasePlatform()->getCountExpression('*'))
+            ->from(UrlAliasGateway::TABLE);
 
-        $statement = $query->prepare();
-        $statement->execute();
+        $statement = $query->execute();
 
         return (int)$statement->fetchColumn();
     }
 
-    protected function dump()
-    {
-        /** @var \eZ\Publish\Core\Persistence\Database\SelectQuery $query */
-        $query = $this->getDatabaseHandler()->createSelectQuery();
-        $query->select(
-            '*'
-        )->from(
-            $this->getDatabaseHandler()->quoteTable('ezurlalias_ml')
-        );
-
-        $statement = $query->prepare();
-        $statement->execute();
-
-        var_dump($statement->fetchAll(\PDO::FETCH_ASSOC));
-    }
-
     /**
      * @var \eZ\Publish\Core\Persistence\Doctrine\ConnectionHandler
      * @deprecated Start to use DBAL $connection instead.
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/Notification/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/Notification/Gateway/DoctrineDatabaseTest.php
index e378bd2937..0bee5a7829 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/Notification/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/Notification/Gateway/DoctrineDatabaseTest.php
@@ -8,11 +8,11 @@
 
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\Notification\Gateway;
 
+use Doctrine\DBAL\FetchMode;
 use eZ\Publish\Core\Persistence\Legacy\Notification\Gateway\DoctrineDatabase;
 use eZ\Publish\Core\Persistence\Legacy\Tests\TestCase;
 use eZ\Publish\SPI\Persistence\Notification\CreateStruct;
 use eZ\Publish\SPI\Persistence\Notification\Notification;
-use PDO;
 
 class DoctrineDatabaseTest extends TestCase
 {
@@ -175,7 +175,7 @@ public function testDelete()
     protected function getGateway(): DoctrineDatabase
     {
         return new DoctrineDatabase(
-            $this->getDatabaseHandler()->getConnection()
+            $this->getDatabaseConnection()
         );
     }
 
@@ -183,7 +183,7 @@ private function loadNotification(int $id): array
     {
         $data = $this->connection
             ->executeQuery('SELECT * FROM eznotification WHERE id = :id', ['id' => $id])
-            ->fetch(PDO::FETCH_ASSOC);
+            ->fetch(FetchMode::ASSOCIATIVE);
 
         return is_array($data) ? $data : [];
     }
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/User/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/User/Gateway/DoctrineDatabaseTest.php
index 69e307ef58..17978680c8 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/User/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/User/Gateway/DoctrineDatabaseTest.php
@@ -8,6 +8,7 @@
 
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\User\Gateway;
 
+use Doctrine\DBAL\ParameterType;
 use eZ\Publish\Core\Persistence\Legacy\Tests\TestCase;
 use eZ\Publish\Core\Persistence\Legacy\User\Gateway\DoctrineDatabase;
 
@@ -43,7 +44,7 @@ public function testRemoveRoleByAssignmentId(): void
         $gateway = $this->getDatabaseGateway();
 
         $gateway->removeRoleAssignmentById(38);
-        $query = $this->getDatabaseHandler()->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
 
         $this->assertQueryResult(
             [
@@ -72,7 +73,12 @@ public function testRemoveRoleByAssignmentId(): void
             $query
                 ->select('contentobject_id', 'id', 'limit_identifier', 'limit_value', 'role_id')
                 ->from('ezuser_role')
-                ->where($query->expr->eq('role_id', $query->bindValue('5')))
+                ->where(
+                    $query->expr()->eq(
+                        'role_id',
+                        $query->createPositionalParameter(5, ParameterType::INTEGER)
+                    )
+                )
         );
     }
 
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/User/Role/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/User/Role/Gateway/DoctrineDatabaseTest.php
index 70a71a5188..f8d083f606 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/User/Role/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/User/Role/Gateway/DoctrineDatabaseTest.php
@@ -8,6 +8,7 @@
 
 namespace eZ\Publish\Core\Persistence\Legacy\Tests\User\Role\Gateway;
 
+use Doctrine\DBAL\ParameterType;
 use eZ\Publish\Core\Persistence\Legacy\Tests\TestCase;
 use eZ\Publish\Core\Persistence\Legacy\User\Role\Gateway\DoctrineDatabase;
 use eZ\Publish\SPI\Persistence\User\Role;
@@ -52,7 +53,7 @@ public function testCreateRole(): void
             'status' => Role::STATUS_DRAFT,
         ]);
         $gateway->createRole($spiRole);
-        $query = $this->getDatabaseHandler()->createSelectQuery();
+        $query = $this->getDatabaseConnection()->createQueryBuilder();
 
         $this->assertQueryResult(
             [
@@ -65,7 +66,12 @@ public function testCreateRole(): void
             $query
                 ->select('id', 'name', 'version')
                 ->from('ezrole')
-                ->where($query->expr->eq('name', $query->bindValue('new_role')))
+                ->where(
+                    $query->expr()->eq(
+                        'name',
+                        $query->createPositionalParameter('new_role', ParameterType::STRING)
+                    )
+                )
         );
     }
 
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/User/UserHandlerTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/User/UserHandlerTest.php
index 5732f874f6..30cbf5ba9e 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/User/UserHandlerTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/User/UserHandlerTest.php
@@ -291,7 +291,7 @@ public function testUpdateUserToken()
 
         $this->assertQueryResult(
             [['0800fc577294c34e0b28ad2839435945', 1, 1234567890, self::TEST_USER_ID]],
-            $this->handler->createSelectQuery()->select(
+            $this->getDatabaseConnection()->createQueryBuilder()->select(
                 ['hash_key', 'id', 'time', 'user_id']
             )->from('ezuser_accountkey'),
             'Expected user data to be updated.'
@@ -301,7 +301,7 @@ public function testUpdateUserToken()
 
         $this->assertQueryResult(
             [['0800fc577294c34e0b28ad2839435945', 1, 2234567890, self::TEST_USER_ID]],
-            $this->handler->createSelectQuery()->select(
+            $this->getDatabaseConnection()->createQueryBuilder()->select(
                 ['hash_key', 'id', 'time', 'user_id']
             )->from('ezuser_accountkey'),
             'Expected user token data to be updated.'
@@ -316,7 +316,7 @@ public function testExpireUserToken()
 
         $this->assertQueryResult(
             [['0800fc577294c34e0b28ad2839435945', 1, 1234567890, self::TEST_USER_ID]],
-            $this->handler->createSelectQuery()->select(
+            $this->getDatabaseConnection()->createQueryBuilder()->select(
                 ['hash_key', 'id', 'time', 'user_id']
             )->from('ezuser_accountkey'),
             'Expected user data to be updated.'
@@ -326,7 +326,7 @@ public function testExpireUserToken()
 
         $this->assertQueryResult(
             [['0800fc577294c34e0b28ad2839435945', 1, 0, self::TEST_USER_ID]],
-            $this->handler->createSelectQuery()->select(
+            $this->getDatabaseConnection()->createQueryBuilder()->select(
                 ['hash_key', 'id', 'time', 'user_id']
             )->from('ezuser_accountkey'),
             'Expected user token to be expired.'
@@ -372,7 +372,7 @@ public function testCreateNewRoleWithoutPolicies()
 
         $this->assertQueryResult(
             [[1, 'Test', -1]],
-            $this->handler->createSelectQuery()->select('id', 'name', 'version')->from('ezrole'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'name', 'version')->from('ezrole'),
             'Expected a new role draft.'
         );
     }
@@ -395,7 +395,7 @@ public function testCreateRoleDraftWithoutPolicies()
                 [$publishedRoleId, 'Test', APIRole::STATUS_DEFINED],
                 [2, 'Test', $publishedRoleId],
             ],
-            $this->handler->createSelectQuery()->select('id', 'name', 'version')->from('ezrole'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'name', 'version')->from('ezrole'),
             'Expected a role and a role draft.'
         );
     }
@@ -573,7 +573,7 @@ public function testUpdateRole()
 
         $this->assertQueryResult(
             [[1, 'Changed']],
-            $this->handler->createSelectQuery()->select('id', 'name')->from('ezrole'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'name')->from('ezrole'),
             'Expected a changed role.'
         );
     }
@@ -588,19 +588,19 @@ public function testDeleteRole()
 
         $this->assertQueryResult(
             [],
-            $this->handler->createSelectQuery()->select('id')->from('ezrole')->where('id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id')->from('ezrole')->where('id = 3'),
             'Expected an empty set.'
         );
 
         $this->assertQueryResult(
             [],
-            $this->handler->createSelectQuery()->select('role_id')->from('ezpolicy')->where('role_id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('role_id')->from('ezpolicy')->where('role_id = 3'),
             'Expected an empty set.'
         );
 
         $this->assertQueryResult(
             [],
-            $this->handler->createSelectQuery()->select('role_id')->from('ezuser_role')->where('role_id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('role_id')->from('ezuser_role')->where('role_id = 3'),
             'Expected an empty set.'
         );
     }
@@ -616,19 +616,19 @@ public function testDeleteRoleDraft()
 
         $this->assertQueryResult(
             [['3', APIRole::STATUS_DEFINED]],
-            $this->handler->createSelectQuery()->select('id, version')->from('ezrole')->where('id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id, version')->from('ezrole')->where('id = 3'),
             'Expected a published role.'
         );
 
         $this->assertQueryResult(
             [[implode("\n", array_fill(0, 28, '3, ' . APIRole::STATUS_DEFINED))]],
-            $this->handler->createSelectQuery()->select('role_id, original_id')->from('ezpolicy')->where('role_id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('role_id, original_id')->from('ezpolicy')->where('role_id = 3'),
             'Expected 28 policies for the published role.'
         );
 
         $this->assertQueryResult(
             [[3], [3]],
-            $this->handler->createSelectQuery()->select('role_id')->from('ezuser_role')->where('role_id = 3'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('role_id')->from('ezuser_role')->where('role_id = 3'),
             'Expected that role assignments still exist.'
         );
     }
@@ -647,7 +647,7 @@ public function testAddPolicyToRoleLimitations()
 
         $this->assertQueryResult(
             [[1, 'foo', 'bar', 1]],
-            $this->handler->createSelectQuery()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy'),
             'Expected a new policy.'
         );
     }
@@ -676,7 +676,7 @@ public function testAddPolicyLimitations()
                 [1, 'Subtree', 1],
                 [2, 'Foo', 1],
             ],
-            $this->handler->createSelectQuery()->select('id', 'identifier', 'policy_id')->from('ezpolicy_limitation'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'identifier', 'policy_id')->from('ezpolicy_limitation'),
             'Expected a new policy.'
         );
     }
@@ -691,7 +691,7 @@ public function testAddPolicyLimitationValues()
                 [2, '/1/2', 1],
                 [3, 'Bar', 2],
             ],
-            $this->handler->createSelectQuery()->select('id', 'value', 'limitation_id')->from('ezpolicy_limitation_value'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'value', 'limitation_id')->from('ezpolicy_limitation_value'),
             'Expected a new policy.'
         );
     }
@@ -731,7 +731,7 @@ public function testImplicitlyCreatePolicies()
                 [1, 'foo', 'bar', 1],
                 [2, 'foo', 'blubb', 1],
             ],
-            $this->handler->createSelectQuery()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy'),
             'Expected a new policy.'
         );
     }
@@ -748,7 +748,7 @@ public function testDeletePolicy()
             [
                 [2, 'foo', 'blubb', 1],
             ],
-            $this->handler->createSelectQuery()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy')->where('original_id = 0'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'module_name', 'function_name', 'role_id')->from('ezpolicy')->where('original_id = 0'),
             'Expected a new policy.'
         );
     }
@@ -762,7 +762,7 @@ public function testDeletePolicyLimitations()
 
         $this->assertQueryResult(
             [[3, 'Foo', 2]],
-            $this->handler->createSelectQuery()->select('*')->from('ezpolicy_limitation')
+            $this->getDatabaseConnection()->createQueryBuilder()->select('*')->from('ezpolicy_limitation')
         );
     }
 
@@ -775,7 +775,7 @@ public function testDeletePolicyLimitationValues()
 
         $this->assertQueryResult(
             [[4, 3, 'Blubb']],
-            $this->handler->createSelectQuery()->select('*')->from('ezpolicy_limitation_value')
+            $this->getDatabaseConnection()->createQueryBuilder()->select('*')->from('ezpolicy_limitation_value')
         );
     }
 
@@ -797,7 +797,7 @@ public function testUpdatePolicies()
                 [3, 'Foo', 2],
                 [4, 'new', 1],
             ],
-            $this->handler->createSelectQuery()->select('*')->from('ezpolicy_limitation')
+            $this->getDatabaseConnection()->createQueryBuilder()->select('*')->from('ezpolicy_limitation')
         );
 
         $this->assertQueryResult(
@@ -805,7 +805,7 @@ public function testUpdatePolicies()
                 [4, 3, 'Blubb'],
                 [5, 4, 'something'],
             ],
-            $this->handler->createSelectQuery()->select('*')->from('ezpolicy_limitation_value')
+            $this->getDatabaseConnection()->createQueryBuilder()->select('*')->from('ezpolicy_limitation_value')
         );
     }
 
@@ -824,7 +824,7 @@ public function testAddRoleToUser()
             [
                 [1, self::TEST_USER_ID, 1, null, null],
             ],
-            $this->handler->createSelectQuery()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
             'Expected a new user policy association.'
         );
     }
@@ -850,7 +850,7 @@ public function testAddRoleToUserWithLimitation()
             [
                 [1, self::TEST_USER_ID, 1, 'Subtree', '/1'],
             ],
-            $this->handler->createSelectQuery()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
             'Expected a new user policy association.'
         );
     }
@@ -879,7 +879,7 @@ public function testAddRoleToUserWithComplexLimitation()
                 [2, self::TEST_USER_ID, 1, 'Subtree', '/1/2'],
                 [3, self::TEST_USER_ID, 1, 'Foo', 'Bar'],
             ],
-            $this->handler->createSelectQuery()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
             'Expected a new user policy association.'
         );
     }
@@ -906,7 +906,7 @@ public function testRemoveUserRoleAssociation()
 
         $this->assertQueryResult(
             [],
-            $this->handler->createSelectQuery()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
+            $this->getDatabaseConnection()->createQueryBuilder()->select('id', 'contentobject_id', 'role_id', 'limit_identifier', 'limit_value')->from('ezuser_role'),
             'Expected no user policy associations.'
         );
     }
diff --git a/eZ/Publish/Core/Persistence/Legacy/Tests/UserPreference/Gateway/DoctrineDatabaseTest.php b/eZ/Publish/Core/Persistence/Legacy/Tests/UserPreference/Gateway/DoctrineDatabaseTest.php
index 30c3bbcd05..4d2c5b5c53 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Tests/UserPreference/Gateway/DoctrineDatabaseTest.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Tests/UserPreference/Gateway/DoctrineDatabaseTest.php
@@ -121,7 +121,7 @@ public function testLoadUserPreferences()
     protected function getGateway(): Gateway
     {
         return new DoctrineDatabase(
-            $this->getDatabaseHandler()->getConnection()
+            $this->getDatabaseConnection()
         );
     }
 
diff --git a/eZ/Publish/SPI/Tests/FieldType/ImageIntegrationTest.php b/eZ/Publish/SPI/Tests/FieldType/ImageIntegrationTest.php
index 5e3bf514a3..6f530f520d 100644
--- a/eZ/Publish/SPI/Tests/FieldType/ImageIntegrationTest.php
+++ b/eZ/Publish/SPI/Tests/FieldType/ImageIntegrationTest.php
@@ -15,6 +15,7 @@
 use eZ\Publish\Core\FieldType\Image\AliasCleanerInterface;
 use eZ\Publish\SPI\Persistence\Content;
 use eZ\Publish\SPI\Persistence\Content\Field;
+use PHPUnit\Framework\MockObject\MockObject;
 use RecursiveIteratorIterator;
 use RecursiveDirectoryIterator;
 use FileSystemIterator;
@@ -90,7 +91,7 @@ public function getCustomHandler()
             new FieldType\Image\ImageStorage(
                 new FieldType\Image\ImageStorage\Gateway\DoctrineStorage(
                     $urlRedecorator,
-                    $this->getDatabaseHandler()->getConnection()
+                    $this->getDatabaseConnection()
                 ),
                 $this->ioService,
                 new FieldType\Image\PathGenerator\LegacyPathGenerator(),
@@ -101,7 +102,10 @@ public function getCustomHandler()
         );
     }
 
-    public function getDeprecationWarnerMock()
+    /**
+     * @return \eZ\Publish\Core\Base\Utils\DeprecationWarnerInterface|\PHPUnit\Framework\MockObject\MockObject
+     */
+    public function getDeprecationWarnerMock(): MockObject
     {
         if (!isset($this->deprecationWarnerMock)) {
             $this->deprecationWarnerMock = $this->createMock(DeprecationWarnerInterface::class);
@@ -110,7 +114,10 @@ public function getDeprecationWarnerMock()
         return $this->deprecationWarnerMock;
     }
 
-    public function getAliasCleanerMock()
+    /**
+     * @return \eZ\Publish\Core\FieldType\Image\AliasCleanerInterface|\PHPUnit\Framework\MockObject\MockObject
+     */
+    public function getAliasCleanerMock(): MockObject
     {
         if (!isset($this->aliasCleanerMock)) {
             $this->aliasCleanerMock = $this->createMock(AliasCleanerInterface::class);
diff --git a/eZ/Publish/SPI/Tests/FieldType/KeywordIntegrationTest.php b/eZ/Publish/SPI/Tests/FieldType/KeywordIntegrationTest.php
index 3a797592df..6fe3f77977 100644
--- a/eZ/Publish/SPI/Tests/FieldType/KeywordIntegrationTest.php
+++ b/eZ/Publish/SPI/Tests/FieldType/KeywordIntegrationTest.php
@@ -61,7 +61,7 @@ public function getCustomHandler()
             new Legacy\Content\FieldValue\Converter\KeywordConverter(),
             new FieldType\Keyword\KeywordStorage(
                 new FieldType\Keyword\KeywordStorage\Gateway\DoctrineStorage(
-                    $this->getDatabaseHandler()->getConnection()
+                    $this->getDatabaseConnection()
                 )
             )
         );