diff --git a/appinfo/info.xml b/appinfo/info.xml
index 694b7b6..5c186b1 100644
--- a/appinfo/info.xml
+++ b/appinfo/info.xml
@@ -1,25 +1,26 @@
 <?xml version="1.0"?>
-<info>
+<info xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
+	  xsi:noNamespaceSchemaLocation="https://apps.nextcloud.com/schema/apps/info.xsd">
 	<id>user_external</id>
 	<name>External user support</name>
 	<summary>Use external user authentication methods like IMAP, SMB and FTP</summary>
 	<description>Use external user authentication methods like IMAP, SMB and FTP</description>
-	<category>tools</category>
-	<category>integration</category>
-	<licence>AGPL</licence>
+	<version>0.5.0</version>
+	<licence>agpl</licence>
 	<author>Robin Appelman</author>
+	<types>
+		<prelogin/>
+		<authentication/>
+	</types>
 	<documentation>
 		<admin>https://docs.nextcloud.com/server/15/admin_manual/configuration_user/user_auth_ftp_smb_imap.html</admin>
 	</documentation>
+	<category>tools</category>
+	<category>integration</category>
 	<website>https://github.com/nextcloud/user_external/</website>
 	<bugs>https://github.com/nextcloud/user_external/issues</bugs>
 	<repository type="git">https://github.com/nextcloud/user_external.git</repository>
 	<dependencies>
 		<nextcloud min-version="15" max-version="15" />
 	</dependencies>
-	<version>0.5.0</version>
-	<types>
-		<authentication/>
-		<prelogin/>
-	</types>
 </info>
diff --git a/lib/base.php b/lib/base.php
index a817338..c4da57f 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -6,7 +6,6 @@
  * See the COPYING-README file.
  */
 namespace OCA\user_external;
-use \OC_DB;
 
 /**
  * Base class for external auth implementations that stores users
@@ -40,10 +39,11 @@ abstract class Base extends \OC\User\Backend{
 	 * @return bool
 	 */
 	public function deleteUser($uid) {
-		OC_DB::executeAudited(
-			'DELETE FROM `*PREFIX*users_external` WHERE `uid` = ? AND `backend` = ?',
-			array($uid, $this->backend)
-		);
+		$query = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$query->delete('users_external')
+			->where($query->expr()->eq('uid', $query->createNamedParameter($uid)))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		$query->execute();
 		return true;
 	}
 
@@ -55,11 +55,15 @@ abstract class Base extends \OC\User\Backend{
 	 * @return string display name
 	 */
 	public function getDisplayName($uid) {
-		$user = OC_DB::executeAudited(
-			'SELECT `displayname` FROM `*PREFIX*users_external`'
-			. ' WHERE `uid` = ? AND `backend` = ?',
-			array($uid, $this->backend)
-		)->fetchRow();
+		$query = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$query->select('displayname')
+			->from('users_external')
+			->where($query->expr()->eq('uid', $query->createNamedParameter($uid)))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		$result = $query->execute();
+		$user = $result->fetch();
+		$result->closeCursor();
+
 		$displayName = trim($user['displayname'], ' ');
 		if (!empty($displayName)) {
 			return $displayName;
@@ -74,21 +78,27 @@ abstract class Base extends \OC\User\Backend{
 	 * @return array with all displayNames (value) and the corresponding uids (key)
 	 */
 	public function getDisplayNames($search = '', $limit = null, $offset = null) {
-		$result = OC_DB::executeAudited(
-			array(
-				'sql' => 'SELECT `uid`, `displayname` FROM `*PREFIX*users_external`'
-					. ' WHERE (LOWER(`displayname`) LIKE LOWER(?) '
-					. ' OR LOWER(`uid`) LIKE LOWER(?)) AND `backend` = ?',
-				'limit'  => $limit,
-				'offset' => $offset
-			),
-			array('%' . $search . '%', '%' . $search . '%', $this->backend)
-		);
 
-		$displayNames = array();
-		while ($row = $result->fetchRow()) {
+		$connection = \OC::$server->getDatabaseConnection();
+		$query = $connection->getQueryBuilder();
+		$query->select('uid', 'displayname')
+			->from('users_external')
+			->where($query->expr()->iLike('displayname', $query->createNamedParameter('%' . $connection->escapeLikeParameter($search) . '%')))
+			->andWhere($query->expr()->iLike('uid', $query->createNamedParameter('%' . $connection->escapeLikeParameter($search) . '%')))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		if ($limit) {
+			$query->setMaxResults($limit);
+		}
+		if ($offset) {
+			$query->setFirstResult($offset);
+		}
+		$result = $query->execute();
+
+		$displayNames = [];
+		while ($row = $result->fetch()) {
 			$displayNames[$row['uid']] = $row['displayname'];
 		}
+		$result->closeCursor();
 
 		return $displayNames;
 	}
@@ -99,19 +109,26 @@ abstract class Base extends \OC\User\Backend{
 	* @return array with all uids
 	*/
 	public function getUsers($search = '', $limit = null, $offset = null) {
-		$result = OC_DB::executeAudited(
-			array(
-				'sql' => 'SELECT `uid` FROM `*PREFIX*users_external`'
-					. ' WHERE LOWER(`uid`) LIKE LOWER(?) AND `backend` = ?',
-				'limit' => $limit,
-				'offset' => $offset
-			),
-			array($search . '%', $this->backend)
-		);
-		$users = array();
-		while ($row = $result->fetchRow()) {
+		$connection = \OC::$server->getDatabaseConnection();
+		$query = $connection->getQueryBuilder();
+		$query->select('uid')
+			->from('users_external')
+			->where($query->expr()->iLike('uid', $query->createNamedParameter($connection->escapeLikeParameter($search) . '%')))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		if ($limit) {
+			$query->setMaxResults($limit);
+		}
+		if ($offset) {
+			$query->setFirstResult($offset);
+		}
+		$result = $query->execute();
+
+		$users = [];
+		while ($row = $result->fetch()) {
 			$users[] = $row['uid'];
 		}
+		$result->closeCursor();
+
 		return $users;
 	}
 
@@ -136,11 +153,14 @@ abstract class Base extends \OC\User\Backend{
 		if (!$this->userExists($uid)) {
 			return false;
 		}
-		OC_DB::executeAudited(
-			'UPDATE `*PREFIX*users_external` SET `displayname` = ?'
-			. ' WHERE LOWER(`uid`) = ? AND `backend` = ?',
-			array($displayName, $uid, $this->backend)
-		);
+
+		$query = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+		$query->update('users_external')
+			->set('displayname', $query->createNamedParameter($displayName))
+			->where($query->expr()->eq('uid', $query->createNamedParameter($uid)))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		$query->execute();
+
 		return true;
 	}
 
@@ -154,11 +174,14 @@ abstract class Base extends \OC\User\Backend{
 	protected function storeUser($uid)
 	{
 		if (!$this->userExists($uid)) {
-			OC_DB::executeAudited(
-				'INSERT INTO `*PREFIX*users_external` ( `uid`, `backend` )'
-				. ' VALUES( ?, ? )',
-				array($uid, $this->backend)
-			);
+
+			$query = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+			$query->insert('users_external')
+				->values([
+					'uid' => $query->createNamedParameter($uid),
+					'backend' => $query->createNamedParameter($this->backend),
+				]);
+			$query->execute();
 		}
 	}
 
@@ -170,11 +193,16 @@ abstract class Base extends \OC\User\Backend{
 	 * @return boolean
 	 */
 	public function userExists($uid) {
-		$result = OC_DB::executeAudited(
-			'SELECT COUNT(*) FROM `*PREFIX*users_external`'
-			. ' WHERE LOWER(`uid`) = LOWER(?) AND `backend` = ?',
-			array($uid, $this->backend)
-		);
-		return $result->fetchOne() > 0;
+		$connection = \OC::$server->getDatabaseConnection();
+		$query = $connection->getQueryBuilder();
+		$query->select($query->func()->count('*', 'num_users'))
+			->from('users_external')
+			->where($query->expr()->iLike('uid', $query->createNamedParameter($connection->escapeLikeParameter($uid))))
+			->andWhere($query->expr()->eq('backend', $query->createNamedParameter($this->backend)));
+		$result = $query->execute();
+		$users = $result->fetchColumn();
+		$result->closeCursor();
+
+		return $users > 0;
 	}
 }
diff --git a/lib/ftp.php b/lib/ftp.php
index 1652b82..ce9ae19 100644
--- a/lib/ftp.php
+++ b/lib/ftp.php
@@ -46,9 +46,9 @@ class OC_User_FTP extends \OCA\user_external\Base{
 	 */
 	public function checkPassword($uid, $password) {
 		if (false === array_search($this->protocol, stream_get_wrappers())) {
-			OCP\Util::writeLog(
-				'user_external',
-				'ERROR: Stream wrapper not available: ' . $this->protocol, OCP\Util::ERROR
+			OC::$server->getLogger()->error(
+				'ERROR: Stream wrapper not available: ' . $this->protocol,
+				['app' => 'user_external']
 			);
 			return false;
 		}
diff --git a/lib/imap.php b/lib/imap.php
index 046ba94..a412da2 100644
--- a/lib/imap.php
+++ b/lib/imap.php
@@ -42,7 +42,7 @@ class OC_User_IMAP extends \OCA\user_external\Base {
 	 */
 	public function checkPassword($uid, $password) {
 		if (!function_exists('imap_open')) {
-			OCP\Util::writeLog('user_external', 'ERROR: PHP imap extension is not installed', OCP\Util::ERROR);
+			OC::$server->getLogger()->error('ERROR: PHP imap extension is not installed', ['app' => 'user_external']);
 			return false;
 		}
 
@@ -52,44 +52,30 @@ class OC_User_IMAP extends \OCA\user_external\Base {
 			$uid = str_replace("%40","@",$uid);
 		}
 
-                $result = OC_DB::executeAudited(
-                        'SELECT `userid` FROM `*PREFIX*preferences` WHERE `appid`=? AND `configkey`=? AND `configvalue`=?',
-                        array('settings','email',$uid)
-                );
-
-		$users = array();
-		while ($row = $result->fetchRow()) {
-			$users[] = $row['userid'];
-		}
-
-		if(count($users) === 1) {
+		if ($this->domain !== '') {
+			$pieces = explode('@', $uid);
+			if (count($pieces) === 1) {
+				$username = $uid . '@' . $this->domain;
+			} else if(count($pieces) === 2 && $pieces[1] === $this->domain) {
+				$username = $uid;
+				$uid = $pieces[0];
+			} else {
+				return false;
+			}
+		} else {
 			$username = $uid;
-			$uid = $users[0];
- 		// Check if we only want logins from ONE domain and strip the domain part from UID		
-		}elseif($this->domain != '') {
- 			$pieces = explode('@', $uid);
- 			if(count($pieces) == 1) {
- 				$username = $uid . "@" . $this->domain;
- 			}elseif((count($pieces) == 2) and ($pieces[1] == $this->domain)) {
- 				$username = $uid;
- 				$uid = $pieces[0];
- 			}else{
- 				return false;
- 			}
- 		}else{
- 			$username = $uid;
  		}
- 
- 		$mbox = @imap_open($this->mailbox, $username, $password, OP_HALFOPEN, 1);
+
+		$mbox = @imap_open($this->mailbox, $username, $password, OP_HALFOPEN, 1);
 		imap_errors();
 		imap_alerts();
-		if($mbox !== FALSE) {
+		if($mbox !== false) {
 			imap_close($mbox);
 			$uid = mb_strtolower($uid);
 			$this->storeUser($uid);
 			return $uid;
-		}else{
-			return false;
 		}
+
+		return false;
 	}
 }
diff --git a/lib/smb.php b/lib/smb.php
index f2595a1..d0da14f 100644
--- a/lib/smb.php
+++ b/lib/smb.php
@@ -42,9 +42,9 @@ class OC_User_SMB extends \OCA\user_external\Base{
 		$command = self::SMBCLIENT.' '.escapeshellarg('//' . $this->host . '/dummy').' -U'.$uidEscaped.'%'.$password;
 		$lastline = exec($command, $output, $retval);
 		if ($retval === 127) {
-			OCP\Util::writeLog(
-				'user_external', 'ERROR: smbclient executable missing',
-				OCP\Util::ERROR
+			OC::$server->getLogger()->error(
+				'ERROR: smbclient executable missing',
+				['app' => 'user_external']
 			);
 			return false;
 		} else if (strpos($lastline, self::LOGINERROR) !== false) {
@@ -53,11 +53,11 @@ class OC_User_SMB extends \OCA\user_external\Base{
 		} else if (strpos($lastline, 'NT_STATUS_BAD_NETWORK_NAME') !== false) {
 			//login on minor error
 			goto login;
-		} else if ($retval != 0) {
+		} else if ($retval !== 0) {
 			//some other error
-			OCP\Util::writeLog(
-				'user_external', 'ERROR: smbclient error: ' . trim($lastline),
-				OCP\Util::ERROR
+			OC::$server->getLogger()->error(
+				'ERROR: smbclient error: ' . trim($lastline),
+				['app' => 'user_external']
 			);
 			return false;
 		} else {
@@ -91,4 +91,3 @@ class OC_User_SMB extends \OCA\user_external\Base{
 		return false;
 	}
 }
-
diff --git a/lib/webdavauth.php b/lib/webdavauth.php
index 65ea7b7..747f9ac 100644
--- a/lib/webdavauth.php
+++ b/lib/webdavauth.php
@@ -28,14 +28,14 @@ class WebDavAuth extends Base {
 	public function checkPassword($uid, $password) {
 		$arr = explode('://', $this->webDavAuthUrl, 2);
 		if( ! isset($arr) OR count($arr) !== 2) {
-			\OCP\Util::writeLog('OC_USER_WEBDAVAUTH', 'Invalid Url: "'.$this->webDavAuthUrl.'" ', 3);
+			OC::$server->getLogger()->error('ERROR: Invalid WebdavUrl: "'.$this->webDavAuthUrl.'" ', ['app' => 'user_external']);
 			return false;
 		}
 		list($protocol, $path) = $arr;
 		$url= $protocol.'://'.urlencode($uid).':'.urlencode($password).'@'.$path;
 		$headers = get_headers($url);
-		if($headers==false) {
-			\OCP\Util::writeLog('OC_USER_WEBDAVAUTH', 'Not possible to connect to WebDAV Url: "'.$protocol.'://'.$path.'" ', 3);
+		if($headers === false) {
+			OC::$server->getLogger()->error('ERROR: Not possible to connect to WebDAV Url: "'.$protocol.'://'.$path.'" ', ['app' => 'user_external']);
 			return false;
 
 		}