diff --git a/core/includes/Drupal/Database/Driver/mysql/Connection.php b/core/includes/Drupal/Database/Driver/mysql/Connection.php
index 6daf67b5348..7b694de0c4a 100644
--- a/core/includes/Drupal/Database/Driver/mysql/Connection.php
+++ b/core/includes/Drupal/Database/Driver/mysql/Connection.php
@@ -3,6 +3,7 @@
 namespace Drupal\Database\Driver\mysql;
 
 use Drupal\Database\Database;
+use Drupal\Database\DatabaseTransactionCommitFailedException;
 use Drupal\Database\Connection as DatabaseConnection;
 
 use PDO;
diff --git a/core/includes/Drupal/Database/Query/Insert.php b/core/includes/Drupal/Database/Query/Insert.php
index 76c924c903f..29ef4341496 100644
--- a/core/includes/Drupal/Database/Query/Insert.php
+++ b/core/includes/Drupal/Database/Query/Insert.php
@@ -3,6 +3,8 @@
 namespace Drupal\Database\Query;
 
 use Drupal\Database\Database;
+use Drupal\Database\NoFieldsException;
+use Drupal\Database\FieldsOverlapException;
 
 /**
  * General class for an abstracted INSERT query.
diff --git a/core/includes/Drupal/Database/Query/Merge.php b/core/includes/Drupal/Database/Query/Merge.php
index 2fea04139c6..6829feb13b1 100644
--- a/core/includes/Drupal/Database/Query/Merge.php
+++ b/core/includes/Drupal/Database/Query/Merge.php
@@ -4,6 +4,8 @@ namespace Drupal\Database\Query;
 
 use Drupal\Database\Database;
 use Drupal\Database\Connection;
+use Drupal\Database\InvalidMergeQueryException;
+
 use Exception;
 
 /**
diff --git a/core/modules/search/search.extender.inc b/core/modules/search/search.extender.inc
index ad4b86e8961..5150f4f4c3f 100644
--- a/core/modules/search/search.extender.inc
+++ b/core/modules/search/search.extender.inc
@@ -1,5 +1,8 @@
 <?php
 
+use Drupal\Database\Query\SelectExtender;
+use Drupal\Database\DatabaseStatementEmpty;
+
 /**
  * @file
  * Search query extender and helper functions.
@@ -24,7 +27,7 @@
  * The used query object has the tag 'search_$module' and can be further
  * extended with hook_query_alter().
  */
-class SearchQuery extends SelectQueryExtender {
+class SearchQuery extends SelectExtender {
   /**
    * The search query that is used for searching.
    *
diff --git a/core/modules/simpletest/drupal_web_test_case.php b/core/modules/simpletest/drupal_web_test_case.php
index 0ad11710737..ddde536e39b 100644
--- a/core/modules/simpletest/drupal_web_test_case.php
+++ b/core/modules/simpletest/drupal_web_test_case.php
@@ -1,6 +1,7 @@
 <?php
 
 use Drupal\Database\Database;
+use Drupal\Database\DatabaseConnectionNotDefinedException;
 
 /**
  * Global variable that holds information about the tests being run.
diff --git a/core/modules/simpletest/tests/database_test.test b/core/modules/simpletest/tests/database_test.test
index 32396a4cabb..ec6dade4808 100644
--- a/core/modules/simpletest/tests/database_test.test
+++ b/core/modules/simpletest/tests/database_test.test
@@ -1,6 +1,11 @@
 <?php
 
 use Drupal\Database\Database;
+use Drupal\Database\DatabaseStatementEmpty;
+use Drupal\Database\DatabaseStatementInterface;
+use Drupal\Database\NoFieldsException;
+use Drupal\Database\InvalidMergeQueryException;
+use Drupal\Database\Query\Merge;
 
 /**
  * Dummy class for fetching into a class.
@@ -1091,7 +1096,7 @@ class DatabaseMergeTestCase extends DatabaseTestCase {
       ))
       ->execute();
 
-    $this->assertEqual($result, MergeQuery::STATUS_INSERT, t('Insert status returned.'));
+    $this->assertEqual($result, Merge::STATUS_INSERT, t('Insert status returned.'));
 
     $num_records_after = db_query('SELECT COUNT(*) FROM {test_people}')->fetchField();
     $this->assertEqual($num_records_before + 1, $num_records_after, t('Merge inserted properly.'));
@@ -1116,7 +1121,7 @@ class DatabaseMergeTestCase extends DatabaseTestCase {
       ))
       ->execute();
 
-    $this->assertEqual($result, MergeQuery::STATUS_UPDATE, t('Update status returned.'));
+    $this->assertEqual($result, Merge::STATUS_UPDATE, t('Update status returned.'));
 
     $num_records_after = db_query('SELECT COUNT(*) FROM {test_people}')->fetchField();
     $this->assertEqual($num_records_before, $num_records_after, t('Merge updated properly.'));