diff --git a/apps/federatedfilesharing/lib/Controller/RequestHandlerController.php b/apps/federatedfilesharing/lib/Controller/RequestHandlerController.php
index bc81db50b2..90346546a2 100644
--- a/apps/federatedfilesharing/lib/Controller/RequestHandlerController.php
+++ b/apps/federatedfilesharing/lib/Controller/RequestHandlerController.php
@@ -427,9 +427,19 @@ class RequestHandlerController extends OCSController {
 
 		$token = isset($_POST['token']) ? $_POST['token'] : null;
 
-		$query = \OCP\DB::prepare('SELECT * FROM `*PREFIX*share_external` WHERE `remote_id` = ? AND `share_token` = ?');
-		$query->execute(array($id, $token));
-		$share = $query->fetchRow();
+		$qb = $this->connection->getQueryBuilder();
+		$qb->select('*')
+			->from('share_external')
+			->where(
+				$qb->expr()->andX(
+					$qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
+					$qb->expr()->eq('share_token', $qb->createNamedParameter($token))
+				)
+			);
+
+		$result = $qb->execute();
+		$share = $result->fetch();
+		$result->closeCursor();
 
 		if ($token && $id && !empty($share)) {
 
@@ -439,8 +449,17 @@ class RequestHandlerController extends OCSController {
 			$mountpoint = $share['mountpoint'];
 			$user = $share['user'];
 
-			$query = \OCP\DB::prepare('DELETE FROM `*PREFIX*share_external` WHERE `remote_id` = ? AND `share_token` = ?');
-			$query->execute(array($id, $token));
+			$qb = $this->connection->getQueryBuilder();
+			$qb->delete('share_external')
+				->where(
+					$qb->expr()->andX(
+						$qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
+						$qb->expr()->eq('share_token', $qb->createNamedParameter($token))
+					)
+				);
+
+			$result = $qb->execute();
+			$result->closeCursor();
 
 			if ($share['accepted']) {
 				$path = trim($mountpoint, '/');
diff --git a/apps/federatedfilesharing/tests/Controller/RequestHandlerControllerTest.php b/apps/federatedfilesharing/tests/Controller/RequestHandlerControllerTest.php
index 035b7da15c..d76f93751a 100644
--- a/apps/federatedfilesharing/tests/Controller/RequestHandlerControllerTest.php
+++ b/apps/federatedfilesharing/tests/Controller/RequestHandlerControllerTest.php
@@ -119,11 +119,13 @@ class RequestHandlerControllerTest extends TestCase {
 	}
 
 	protected function tearDown() {
-		$query = \OCP\DB::prepare('DELETE FROM `*PREFIX*share_external`');
-		$query->execute();
+		$qb = $this->connection->getQueryBuilder();
+		$qb->delete('share_external');
+		$qb->execute();
 
-		$query = \OCP\DB::prepare('DELETE FROM `*PREFIX*share`');
-		$query->execute();
+		$qb = $this->connection->getQueryBuilder();
+		$qb->delete('share');
+		$qb->execute();
 
 		parent::tearDown();
 	}
@@ -142,9 +144,15 @@ class RequestHandlerControllerTest extends TestCase {
 
 		$this->s2s->createShare(null);
 
-		$query = \OCP\DB::prepare('SELECT * FROM `*PREFIX*share_external` WHERE `remote_id` = ?');
-		$result = $query->execute(array('1'));
-		$data = $result->fetchRow();
+		$qb = $this->connection->getQueryBuilder();
+		$qb->select('*')
+			->from('share_external')
+			->where(
+				$qb->expr()->eq('remote_id', $qb->createNamedParameter(1))
+			);
+		$result = $qb->execute();
+		$data = $result->fetch();
+		$result->closeCursor();
 
 		$this->assertSame('localhost', $data['remote']);
 		$this->assertSame('token', $data['share_token']);
@@ -187,7 +195,7 @@ class RequestHandlerControllerTest extends TestCase {
 
 		$this->share->expects($this->any())->method('verifyShare')->willReturn(true);
 
-		$dummy = \OCP\DB::prepare('
+		$dummy = \OC_DB::prepare('
 			INSERT INTO `*PREFIX*share`
 			(`share_type`, `uid_owner`, `item_type`, `item_source`, `item_target`, `file_source`, `file_target`, `permissions`, `stime`, `token`, `share_with`)
 			VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
@@ -195,7 +203,7 @@ class RequestHandlerControllerTest extends TestCase {
 		$dummy->execute(array(\OCP\Share::SHARE_TYPE_REMOTE, self::TEST_FILES_SHARING_API_USER1, 'test', '1', '/1', '1', '/test.txt', '1', time(), 'token1', 'foo@bar'));
 		$dummy->execute(array(\OCP\Share::SHARE_TYPE_REMOTE, self::TEST_FILES_SHARING_API_USER1, 'test', '1', '/1', '1', '/test.txt', '1', time(), 'token2', 'bar@bar'));
 
-		$verify = \OCP\DB::prepare('SELECT * FROM `*PREFIX*share`');
+		$verify = \OC_DB::prepare('SELECT * FROM `*PREFIX*share`');
 		$result = $verify->execute();
 		$data = $result->fetchAll();
 		$this->assertCount(2, $data);
@@ -203,7 +211,7 @@ class RequestHandlerControllerTest extends TestCase {
 		$_POST['token'] = 'token1';
 		$this->s2s->declineShare(array('id' => $data[0]['id']));
 
-		$verify = \OCP\DB::prepare('SELECT * FROM `*PREFIX*share`');
+		$verify = \OC_DB::prepare('SELECT * FROM `*PREFIX*share`');
 		$result = $verify->execute();
 		$data = $result->fetchAll();
 		$this->assertCount(1, $data);
@@ -212,7 +220,7 @@ class RequestHandlerControllerTest extends TestCase {
 		$_POST['token'] = 'token2';
 		$this->s2s->declineShare(array('id' => $data[0]['id']));
 
-		$verify = \OCP\DB::prepare('SELECT * FROM `*PREFIX*share`');
+		$verify = \OC_DB::prepare('SELECT * FROM `*PREFIX*share`');
 		$result = $verify->execute();
 		$data = $result->fetchAll();
 		$this->assertEmpty($data);
diff --git a/apps/files_sharing/lib/ShareBackend/File.php b/apps/files_sharing/lib/ShareBackend/File.php
index e09591b37c..dc1018f88a 100644
--- a/apps/files_sharing/lib/ShareBackend/File.php
+++ b/apps/files_sharing/lib/ShareBackend/File.php
@@ -207,8 +207,15 @@ class File implements \OCP\Share_Backend_File_Dependent {
 		if (isset($source['parent'])) {
 			$parent = $source['parent'];
 			while (isset($parent)) {
-				$query = \OCP\DB::prepare('SELECT `parent`, `uid_owner` FROM `*PREFIX*share` WHERE `id` = ?', 1);
-				$item = $query->execute(array($parent))->fetchRow();
+				$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+				$qb->select('parent', 'uid_owner')
+					->from('share')
+					->where(
+						$qb->expr()->eq('id', $qb->createNamedParameter($parent))
+					);
+				$result = $qb->execute();
+				$item = $result->fetch();
+				$result->closeCursor();
 				if (isset($item['parent'])) {
 					$parent = $item['parent'];
 				} else {
diff --git a/apps/files_sharing/lib/ShareBackend/Folder.php b/apps/files_sharing/lib/ShareBackend/Folder.php
index c48a26300a..0bb67e49b6 100644
--- a/apps/files_sharing/lib/ShareBackend/Folder.php
+++ b/apps/files_sharing/lib/ShareBackend/Folder.php
@@ -70,35 +70,62 @@ class Folder extends File implements \OCP\Share_Backend_Collection {
 	 * @return mixed parent ID or null
 	 */
 	private function getParentId($child) {
-		$query = \OCP\DB::prepare('SELECT `parent` FROM `*PREFIX*filecache` WHERE `fileid` = ?');
-		$result = $query->execute(array($child));
-		$row = $result->fetchRow();
+		$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$qb->select('parent')
+			->from('filecache')
+			->where(
+				$qb->expr()->eq('fileid', $qb->createNamedParameter($child))
+			);
+		$result = $qb->execute();
+		$row = $result->fetch();
+		$result->closeCursor();
 		return $row ? $row['parent'] : null;
 	}
 
 	public function getChildren($itemSource) {
 		$children = array();
 		$parents = array($itemSource);
-		$query = \OCP\DB::prepare('SELECT `id` FROM `*PREFIX*mimetypes` WHERE `mimetype` = ?');
-		$result = $query->execute(array('httpd/unix-directory'));
+
+		$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$qb->select('id')
+			->from('mimetypes')
+			->where(
+				$qb->expr()->eq('mimetype', $qb->createNamedParameter('httpd/unix-directory'))
+			);
+		$result = $qb->execute();
+		$row = $result->fetch();
+		$result->closeCursor();
+
 		if ($row = $result->fetchRow()) {
 			$mimetype = (int) $row['id'];
 		} else {
 			$mimetype = -1;
 		}
 		while (!empty($parents)) {
-			$parents = "'".implode("','", $parents)."'";
-			$query = \OCP\DB::prepare('SELECT `fileid`, `name`, `mimetype` FROM `*PREFIX*filecache`'
-				.' WHERE `parent` IN ('.$parents.')');
-			$result = $query->execute();
+
+			$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+
+			$parents = array_map(function($parent) use ($qb) {
+				return $qb->createNamedParameter($parent);
+			}, $parents);
+
+			$qb->select('`fileid', 'name', '`mimetype')
+				->from('filecache')
+				->where(
+					$qb->expr()->in('parent', $parents)
+				);
+
+			$result = $qb->execute();
+
 			$parents = array();
-			while ($file = $result->fetchRow()) {
+			while ($file = $result->fetch()) {
 				$children[] = array('source' => $file['fileid'], 'file_path' => $file['name']);
 				// If a child folder is found look inside it
 				if ((int) $file['mimetype'] === $mimetype) {
 					$parents[] = $file['fileid'];
 				}
 			}
+			$result->closeCursor();
 		}
 		return $children;
 	}
diff --git a/apps/files_sharing/tests/ShareTest.php b/apps/files_sharing/tests/ShareTest.php
index 9b60255ed9..ca649768d7 100644
--- a/apps/files_sharing/tests/ShareTest.php
+++ b/apps/files_sharing/tests/ShareTest.php
@@ -63,10 +63,6 @@ class ShareTest extends TestCase {
 
 		self::$tempStorage = null;
 
-		// clear database table
-		$query = \OCP\DB::prepare('DELETE FROM `*PREFIX*share`');
-		$query->execute();
-
 		parent::tearDown();
 	}
 
diff --git a/apps/files_sharing/tests/TestCase.php b/apps/files_sharing/tests/TestCase.php
index 3b1ccb71a9..e49b696e68 100644
--- a/apps/files_sharing/tests/TestCase.php
+++ b/apps/files_sharing/tests/TestCase.php
@@ -120,8 +120,9 @@ abstract class TestCase extends \Test\TestCase {
 	}
 
 	protected function tearDown() {
-		$query = \OCP\DB::prepare('DELETE FROM `*PREFIX*share`');
-		$query->execute();
+		$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$qb->delete('share');
+		$qb->execute();
 
 		parent::tearDown();
 	}
@@ -206,16 +207,15 @@ abstract class TestCase extends \Test\TestCase {
 	 * @return array with: item_source, share_type, share_with, item_type, permissions
 	 */
 	protected function getShareFromId($shareID) {
-		$sql = 'SELECT `item_source`, `share_type`, `share_with`, `item_type`, `permissions` FROM `*PREFIX*share` WHERE `id` = ?';
-		$args = array($shareID);
-		$query = \OCP\DB::prepare($sql);
-		$result = $query->execute($args);
-
-		$share = Null;
-
-		if ($result) {
-			$share = $result->fetchRow();
-		}
+		$qb = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$qb->select('item_source', '`share_type', 'share_with', 'item_type', 'permissions')
+			->from('share')
+			->where(
+				$qb->expr()->eq('id', $qb->createNamedParameter($shareID))
+			);
+		$result = $qb->execute();
+		$share = $result->fetch();
+		$result->closeCursor();
 
 		return $share;
 
diff --git a/apps/user_ldap/lib/Helper.php b/apps/user_ldap/lib/Helper.php
index fb5b547810..a4bac9667b 100644
--- a/apps/user_ldap/lib/Helper.php
+++ b/apps/user_ldap/lib/Helper.php
@@ -155,7 +155,7 @@ class Helper {
 			$saveOtherConfigurations = 'AND `configkey` NOT LIKE \'s%\'';
 		}
 
-		$query = \OCP\DB::prepare('
+		$query = \OC_DB::prepare('
 			DELETE
 			FROM `*PREFIX*appconfig`
 			WHERE `configkey` LIKE ?
diff --git a/apps/user_ldap/lib/Jobs/UpdateGroups.php b/apps/user_ldap/lib/Jobs/UpdateGroups.php
index c5eff77dbe..2b57874c62 100644
--- a/apps/user_ldap/lib/Jobs/UpdateGroups.php
+++ b/apps/user_ldap/lib/Jobs/UpdateGroups.php
@@ -93,7 +93,7 @@ class UpdateGroups extends \OC\BackgroundJob\TimedJob {
 	 */
 	static private function handleKnownGroups($groups) {
 		\OCP\Util::writeLog('user_ldap', 'bgJ "updateGroups" – Dealing with known Groups.', \OCP\Util::DEBUG);
-		$query = \OCP\DB::prepare('
+		$query = \OC_DB::prepare('
 			UPDATE `*PREFIX*ldap_group_members`
 			SET `owncloudusers` = ?
 			WHERE `owncloudname` = ?
@@ -131,7 +131,7 @@ class UpdateGroups extends \OC\BackgroundJob\TimedJob {
 	 */
 	static private function handleCreatedGroups($createdGroups) {
 		\OCP\Util::writeLog('user_ldap', 'bgJ "updateGroups" – dealing with created Groups.', \OCP\Util::DEBUG);
-		$query = \OCP\DB::prepare('
+		$query = \OC_DB::prepare('
 			INSERT
 			INTO `*PREFIX*ldap_group_members` (`owncloudname`, `owncloudusers`)
 			VALUES (?, ?)
@@ -153,7 +153,7 @@ class UpdateGroups extends \OC\BackgroundJob\TimedJob {
 	 */
 	static private function handleRemovedGroups($removedGroups) {
 		\OCP\Util::writeLog('user_ldap', 'bgJ "updateGroups" – dealing with removed groups.', \OCP\Util::DEBUG);
-		$query = \OCP\DB::prepare('
+		$query = \OC_DB::prepare('
 			DELETE
 			FROM `*PREFIX*ldap_group_members`
 			WHERE `owncloudname` = ?
@@ -212,7 +212,7 @@ class UpdateGroups extends \OC\BackgroundJob\TimedJob {
 		if(is_array(self::$groupsFromDB)) {
 			return self::$groupsFromDB;
 		}
-		$query = \OCP\DB::prepare('
+		$query = \OC_DB::prepare('
 			SELECT `owncloudname`, `owncloudusers`
 			FROM `*PREFIX*ldap_group_members`
 		');
diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 32534c2a9e..66abafab99 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -98,7 +98,6 @@ return array(
     'OCP\\Contacts\\ContactsMenu\\ILinkAction' => $baseDir . '/lib/public/Contacts/ContactsMenu/ILinkAction.php',
     'OCP\\Contacts\\ContactsMenu\\IProvider' => $baseDir . '/lib/public/Contacts/ContactsMenu/IProvider.php',
     'OCP\\Contacts\\IManager' => $baseDir . '/lib/public/Contacts/IManager.php',
-    'OCP\\DB' => $baseDir . '/lib/public/DB.php',
     'OCP\\DB\\ISchemaWrapper' => $baseDir . '/lib/public/DB/ISchemaWrapper.php',
     'OCP\\DB\\QueryBuilder\\ICompositeExpression' => $baseDir . '/lib/public/DB/QueryBuilder/ICompositeExpression.php',
     'OCP\\DB\\QueryBuilder\\IExpressionBuilder' => $baseDir . '/lib/public/DB/QueryBuilder/IExpressionBuilder.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index d37777001b..c33f07a54a 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -128,7 +128,6 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OCP\\Contacts\\ContactsMenu\\ILinkAction' => __DIR__ . '/../../..' . '/lib/public/Contacts/ContactsMenu/ILinkAction.php',
         'OCP\\Contacts\\ContactsMenu\\IProvider' => __DIR__ . '/../../..' . '/lib/public/Contacts/ContactsMenu/IProvider.php',
         'OCP\\Contacts\\IManager' => __DIR__ . '/../../..' . '/lib/public/Contacts/IManager.php',
-        'OCP\\DB' => __DIR__ . '/../../..' . '/lib/public/DB.php',
         'OCP\\DB\\ISchemaWrapper' => __DIR__ . '/../../..' . '/lib/public/DB/ISchemaWrapper.php',
         'OCP\\DB\\QueryBuilder\\ICompositeExpression' => __DIR__ . '/../../..' . '/lib/public/DB/QueryBuilder/ICompositeExpression.php',
         'OCP\\DB\\QueryBuilder\\IExpressionBuilder' => __DIR__ . '/../../..' . '/lib/public/DB/QueryBuilder/IExpressionBuilder.php',
diff --git a/lib/private/Tags.php b/lib/private/Tags.php
index cf1c5c0fba..c78297e529 100644
--- a/lib/private/Tags.php
+++ b/lib/private/Tags.php
@@ -288,7 +288,7 @@ class Tags implements \OCP\ITags {
 			. '` WHERE `categoryid` = ?';
 
 		try {
-			$stmt = \OCP\DB::prepare($sql);
+			$stmt = \OC_DB::prepare($sql);
 			$result = $stmt->execute(array($tagId));
 			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OC::$server->getDatabaseConnection()->getError(), \OCP\Util::ERROR);
@@ -530,7 +530,7 @@ class Tags implements \OCP\ITags {
 		// Find all objectid/tagId pairs.
 		$result = null;
 		try {
-			$stmt = \OCP\DB::prepare('SELECT `id` FROM `' . self::TAG_TABLE . '` '
+			$stmt = \OC_DB::prepare('SELECT `id` FROM `' . self::TAG_TABLE . '` '
 				. 'WHERE `uid` = ?');
 			$result = $stmt->execute(array($arguments['uid']));
 			if ($result === null) {
@@ -546,7 +546,7 @@ class Tags implements \OCP\ITags {
 
 		if(!is_null($result)) {
 			try {
-				$stmt = \OCP\DB::prepare('DELETE FROM `' . self::RELATION_TABLE . '` '
+				$stmt = \OC_DB::prepare('DELETE FROM `' . self::RELATION_TABLE . '` '
 					. 'WHERE `categoryid` = ?');
 				while( $row = $result->fetchRow()) {
 					try {
@@ -568,7 +568,7 @@ class Tags implements \OCP\ITags {
 			}
 		}
 		try {
-			$stmt = \OCP\DB::prepare('DELETE FROM `' . self::TAG_TABLE . '` '
+			$stmt = \OC_DB::prepare('DELETE FROM `' . self::TAG_TABLE . '` '
 				. 'WHERE `uid` = ?');
 			$result = $stmt->execute(array($arguments['uid']));
 			if ($result === null) {
@@ -600,7 +600,7 @@ class Tags implements \OCP\ITags {
 			$query .= 'WHERE `objid` IN (' . str_repeat('?,', count($ids)-1) . '?) ';
 			$query .= 'AND `type`= ?';
 			$updates[] = $this->type;
-			$stmt = \OCP\DB::prepare($query);
+			$stmt = \OC_DB::prepare($query);
 			$result = $stmt->execute($updates);
 			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OC::$server->getDatabaseConnection()->getError(), \OCP\Util::ERROR);
@@ -719,7 +719,7 @@ class Tags implements \OCP\ITags {
 		try {
 			$sql = 'DELETE FROM `' . self::RELATION_TABLE . '` '
 					. 'WHERE `objid` = ? AND `categoryid` = ? AND `type` = ?';
-			$stmt = \OCP\DB::prepare($sql);
+			$stmt = \OC_DB::prepare($sql);
 			$stmt->execute(array($objid, $tagId, $this->type));
 		} catch(\Exception $e) {
 			\OC::$server->getLogger()->logException($e, [
@@ -769,7 +769,7 @@ class Tags implements \OCP\ITags {
 				try {
 					$sql = 'DELETE FROM `' . self::RELATION_TABLE . '` '
 							. 'WHERE `categoryid` = ?';
-					$stmt = \OCP\DB::prepare($sql);
+					$stmt = \OC_DB::prepare($sql);
 					$result = $stmt->execute(array($id));
 					if ($result === null) {
 						\OCP\Util::writeLog('core',
diff --git a/lib/public/DB.php b/lib/public/DB.php
deleted file mode 100644
index 85a34ff37a..0000000000
--- a/lib/public/DB.php
+++ /dev/null
@@ -1,64 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Bart Visscher <bartv@thisnet.nl>
- * @author Dan Bartram <daneybartram@gmail.com>
- * @author Frank Karlitschek <frank@karlitschek.de>
- * @author Joas Schilling <coding@schilljs.com>
- * @author Jörn Friedrich Dreyer <jfd@butonic.de>
- * @author Lukas Reschke <lukas@statuscode.ch>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Robin Appelman <robin@icewind.nl>
- * @author Roeland Jago Douma <roeland@famdouma.nl>
- * @author Thomas Müller <thomas.mueller@tmit.eu>
- * @author Thomas Tanghus <thomas@tanghus.net>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program.  If not, see <http://www.gnu.org/licenses/>
- *
- */
-
-/**
- * Public interface of ownCloud for apps to use.
- * DB Class
- *
- */
-
-// use OCP namespace for all classes that are considered public.
-// This means that they should be used by apps instead of the internal ownCloud classes
-namespace OCP;
-
-/**
- * This class provides access to the internal database system. Use this class exlusively if you want to access databases
- * @deprecated 8.1.0 use methods of \OCP\IDBConnection - \OC::$server->getDatabaseConnection()
- * @since 4.5.0
- */
-class DB {
-	/**
-	 * Prepare a SQL query
-	 * @param string $query Query string
-	 * @param int $limit Limit of the SQL statement
-	 * @param int $offset Offset of the SQL statement
-	 * @return \OC_DB_StatementWrapper prepared SQL query
-	 *
-	 * SQL query via Doctrine prepare(), needs to be execute()'d!
-	 * @deprecated 8.1.0 use prepare() of \OCP\IDBConnection - \OC::$server->getDatabaseConnection()
-	 * @since 4.5.0
-	 */
-	static public function prepare( $query, $limit=null, $offset=null ) {
-		return \OC_DB::prepare($query, $limit, $offset);
-	}
-
-}