diff --git a/.github/workflows/oci.yml b/.github/workflows/oci.yml
new file mode 100644
index 00000000000..4130e985fc5
--- /dev/null
+++ b/.github/workflows/oci.yml
@@ -0,0 +1,73 @@
+name: PHPUnit
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - stable*
+
+env:
+  APP_NAME: spreed
+
+jobs:
+  oci:
+    runs-on: ubuntu-latest
+
+    strategy:
+      # do not stop on another job's failure
+      fail-fast: false
+      matrix:
+        php-versions: ['7.4']
+        databases: ['oci']
+        server-versions: ['master']
+
+    name: php${{ matrix.php-versions }}-${{ matrix.databases }}
+
+    services:
+      oracle:
+        image: deepdiver/docker-oracle-xe-11g # "wnameless/oracle-xe-11g-r2"
+        ports:
+          - "1521:1521"
+
+    steps:
+      - name: Checkout server
+        uses: actions/checkout@v2
+        with:
+          repository: nextcloud/server
+          ref: ${{ matrix.server-versions }}
+
+      - name: Checkout submodules
+        shell: bash
+        run: |
+          auth_header="$(git config --local --get http.https://github.com/.extraheader)"
+          git submodule sync --recursive
+          git -c "http.extraheader=$auth_header" -c protocol.version=2 submodule update --init --force --recursive --depth=1
+
+      - name: Checkout app
+        uses: actions/checkout@v2
+        with:
+          path: apps/${{ env.APP_NAME }}
+
+      - name: Set up php ${{ matrix.php-versions }}
+        uses: "shivammathur/setup-php@v2"
+        with:
+          php-version: ${{ matrix.php-versions }}
+          extensions: mbstring, iconv, fileinfo, intl, oci8
+          tools: phpunit:8.5.2
+          coverage: none
+
+      - name: Set up PHPUnit
+        working-directory: apps/${{ env.APP_NAME }}
+        run: composer i
+
+      - name: Set up Nextcloud
+        run: |
+          mkdir data
+          ./occ maintenance:install --verbose --database=oci --database-name=XE --database-host=127.0.0.1 --database-port=1521 --database-user=autotest --database-pass=owncloud --admin-user admin --admin-pass admin
+          php -f index.php
+          ./occ app:enable --force ${{ env.APP_NAME }}
+
+      - name: PHPUnit
+        working-directory: apps/${{ env.APP_NAME }}/tests/php
+        run: phpunit -c phpunit.xml
diff --git a/lib/Manager.php b/lib/Manager.php
index 57b8d9a1fb2..e5f59ff8c8c 100644
--- a/lib/Manager.php
+++ b/lib/Manager.php
@@ -29,6 +29,7 @@
 use OCA\Talk\Exceptions\RoomNotFoundException;
 use OCA\Talk\Model\Attendee;
 use OCA\Talk\Model\AttendeeMapper;
+use OCA\Talk\Model\SelectHelper;
 use OCA\Talk\Model\SessionMapper;
 use OCA\Talk\Service\ParticipantService;
 use OCP\App\IAppManager;
@@ -120,9 +121,9 @@ public function __construct(IDBConnection $db,
 
 	public function forAllRooms(callable $callback): void {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms');
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r');
 
 		$result = $query->execute();
 		while ($row = $result->fetch()) {
@@ -241,9 +242,10 @@ public function loadLastCommentInfo(int $id): ?IComment {
 
 	public function resetAssignedSignalingServers(ICache $cache): void {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->from('talk_rooms')
-			->where($query->expr()->isNotNull('assigned_hpb'));
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
+			->where($query->expr()->isNotNull('r.assigned_hpb'));
 
 		$result = $query->execute();
 		while ($row = $result->fetch()) {
@@ -264,20 +266,20 @@ public function resetAssignedSignalingServers(ICache $cache): void {
 	 */
 	public function searchRoomsByToken(string $searchToken = '', int $limit = null, int $offset = null): array {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
 			->setMaxResults(1);
 
 		if ($searchToken !== '') {
-			$query->where($query->expr()->iLike('token', $query->createNamedParameter(
+			$query->where($query->expr()->iLike('r.token', $query->createNamedParameter(
 				'%' . $this->db->escapeLikeParameter($searchToken) . '%'
 			)));
 		}
 
 		$query->setMaxResults($limit)
 			->setFirstResult($offset)
-			->orderBy('token', 'ASC');
+			->orderBy('r.token', 'ASC');
 		$result = $query->execute();
 
 		$rooms = [];
@@ -301,13 +303,11 @@ public function searchRoomsByToken(string $searchToken = '', int $limit = null,
 	 */
 	public function getRoomsForUser(string $userId, bool $includeLastMessage = false): array {
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->addSelect('a.*')
-			->addSelect('s.*')
-			->selectAlias('r.id', 'r_id')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_rooms', 'r')
 			->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
 				$query->expr()->eq('a.actor_id', $query->createNamedParameter($userId)),
 				$query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_USERS)),
@@ -355,9 +355,9 @@ public function getListedRoomsForUser(string $userId, string $term = ''): array
 			$allowedListedTypes[] = Room::LISTABLE_USERS;
 		}
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->selectAlias('r.id', 'r_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
 			->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
 				$query->expr()->eq('a.actor_id', $query->createNamedParameter($userId)),
 				$query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_USERS)),
@@ -399,18 +399,16 @@ public function getListedRoomsForUser(string $userId, string $term = ''): array
 	 */
 	public function getRoomForUser(int $roomId, ?string $userId): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->selectAlias('r.id', 'r_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
 			->where($query->expr()->eq('r.id', $query->createNamedParameter($roomId, IQueryBuilder::PARAM_INT)));
 
 		if ($userId !== null) {
 			// Non guest user
-			$query->addSelect('a.*')
-				->addSelect('s.*')
-				->selectAlias('a.id', 'a_id')
-				->selectAlias('s.id', 's_id')
-				->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
+			$helper->selectAttendeesTable($query);
+			$helper->selectSessionsTable($query);
+			$query->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
 					$query->expr()->eq('a.actor_id', $query->createNamedParameter($userId)),
 					$query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_USERS)),
 					$query->expr()->eq('a.room_id', 'r.id')
@@ -463,19 +461,17 @@ public function getRoomForUser(int $roomId, ?string $userId): Room {
 	 */
 	public function getRoomForUserByToken(string $token, ?string $userId, bool $includeLastMessage = false): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->selectAlias('r.id', 'r_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
 			->where($query->expr()->eq('r.token', $query->createNamedParameter($token)))
 			->setMaxResults(1);
 
 		if ($userId !== null) {
 			// Non guest user
-			$query->addSelect('a.*')
-				->addSelect('s.*')
-				->selectAlias('a.id', 'a_id')
-				->selectAlias('s.id', 's_id')
-				->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
+			$helper->selectAttendeesTable($query);
+			$helper->selectSessionsTable($query);
+			$query->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
 					$query->expr()->eq('a.actor_id', $query->createNamedParameter($userId)),
 					$query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_USERS)),
 					$query->expr()->eq('a.room_id', 'r.id')
@@ -534,10 +530,10 @@ public function getRoomForUserByToken(string $token, ?string $userId, bool $incl
 	 */
 	public function getRoomById(int $roomId): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms')
-			->where($query->expr()->eq('id', $query->createNamedParameter($roomId, IQueryBuilder::PARAM_INT)));
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
+			->where($query->expr()->eq('r.id', $query->createNamedParameter($roomId, IQueryBuilder::PARAM_INT)));
 
 		$result = $query->execute();
 		$row = $result->fetch();
@@ -564,13 +560,11 @@ public function getRoomById(int $roomId): Room {
 	 */
 	public function getRoomByActor(string $token, string $actorType, string $actorId): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->addSelect('a.*')
-			->addSelect('s.*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->selectAlias('r.id', 'r_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_rooms', 'r')
 			->leftJoin('r', 'talk_attendees', 'a', $query->expr()->andX(
 				$query->expr()->eq('a.actor_type', $query->createNamedParameter($actorType)),
 				$query->expr()->eq('a.actor_id', $query->createNamedParameter($actorId)),
@@ -615,9 +609,9 @@ public function getRoomByToken(string $token, ?string $preloadUserId = null): Ro
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('r.*')
-			->selectAlias('r.id', 'r_id')
-			->from('talk_rooms', 'r')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
 			->where($query->expr()->eq('r.token', $query->createNamedParameter($token)));
 
 		$result = $query->execute();
@@ -644,11 +638,11 @@ public function getRoomByToken(string $token, ?string $preloadUserId = null): Ro
 	 */
 	public function getRoomByObject(string $objectType, string $objectId): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms')
-			->where($query->expr()->eq('object_type', $query->createNamedParameter($objectType)))
-			->andWhere($query->expr()->eq('object_id', $query->createNamedParameter($objectId)));
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
+			->where($query->expr()->eq('r.object_type', $query->createNamedParameter($objectType)))
+			->andWhere($query->expr()->eq('r.object_id', $query->createNamedParameter($objectId)));
 
 		$result = $query->execute();
 		$row = $result->fetch();
@@ -678,11 +672,11 @@ public function getRoomForSession(?string $userId, ?string $sessionId): Room {
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('r.id', 'r_id')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_sessions', 's')
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_sessions', 's')
 			->leftJoin('s', 'talk_attendees', 'a', $query->expr()->eq('a.id', 's.attendee_id'))
 			->leftJoin('a', 'talk_rooms', 'r', $query->expr()->eq('a.room_id', 'r.id'))
 			->where($query->expr()->eq('s.session_id', $query->createNamedParameter($sessionId)))
@@ -734,11 +728,11 @@ public function getOne2OneRoom(string $participant1, string $participant2): Room
 		$name = json_encode($users);
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms')
-			->where($query->expr()->eq('type', $query->createNamedParameter(Room::ONE_TO_ONE_CALL, IQueryBuilder::PARAM_INT)))
-			->andWhere($query->expr()->eq('name', $query->createNamedParameter($name)));
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
+			->where($query->expr()->eq('r.type', $query->createNamedParameter(Room::ONE_TO_ONE_CALL, IQueryBuilder::PARAM_INT)))
+			->andWhere($query->expr()->eq('r.name', $query->createNamedParameter($name)));
 
 		$result = $query->execute();
 		$row = $result->fetch();
@@ -764,11 +758,11 @@ public function getOne2OneRoom(string $participant1, string $participant2): Room
 	 */
 	public function getChangelogRoom(string $userId): Room {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('id', 'r_id')
-			->from('talk_rooms')
-			->where($query->expr()->eq('type', $query->createNamedParameter(Room::CHANGELOG_CONVERSATION, IQueryBuilder::PARAM_INT)))
-			->andWhere($query->expr()->eq('name', $query->createNamedParameter($userId)));
+		$helper = new SelectHelper();
+		$helper->selectRoomsTable($query);
+		$query->from('talk_rooms', 'r')
+			->where($query->expr()->eq('r.type', $query->createNamedParameter(Room::CHANGELOG_CONVERSATION, IQueryBuilder::PARAM_INT)))
+			->andWhere($query->expr()->eq('r.name', $query->createNamedParameter($userId)));
 
 		$result = $query->execute();
 		$row = $result->fetch();
@@ -953,9 +947,9 @@ protected function getNewToken(): string {
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('id')
-			->from('talk_rooms')
-			->where($query->expr()->eq('token', $query->createParameter('token')));
+		$query->select('r.id')
+			->from('talk_rooms', 'r')
+			->where($query->expr()->eq('r.token', $query->createParameter('token')));
 
 		$i = 0;
 		while ($i < 1000) {
diff --git a/lib/Migration/CreateHelpCommand.php b/lib/Migration/CreateHelpCommand.php
index 8f20ce606f9..f653d27c8aa 100644
--- a/lib/Migration/CreateHelpCommand.php
+++ b/lib/Migration/CreateHelpCommand.php
@@ -44,13 +44,21 @@ public function getName(): string {
 
 	public function run(IOutput $output): void {
 		try {
-			$this->service->find('', 'help');
+			$command = $this->service->find('', 'help');
+			$this->service->update(
+				$command->getId(),
+				'help',
+				'talk',
+				'help',
+				Command::RESPONSE_USER,
+				Command::ENABLED_ALL
+			);
 		} catch (DoesNotExistException $e) {
 			$this->service->create(
 				'',
 				'help',
 				'talk',
-				'',
+				'help',
 				Command::RESPONSE_USER,
 				Command::ENABLED_ALL
 			);
diff --git a/lib/Model/CommandMapper.php b/lib/Model/CommandMapper.php
index 877ce82033f..5142189a75f 100644
--- a/lib/Model/CommandMapper.php
+++ b/lib/Model/CommandMapper.php
@@ -85,8 +85,13 @@ public function find(string $app, string $cmd): Command {
 		$query = $this->db->getQueryBuilder();
 		$query->select('*')
 			->from($this->getTableName())
-			->where($query->expr()->eq('app', $query->createNamedParameter($app)))
-			->andWhere($query->expr()->eq('command', $query->createNamedParameter($cmd)));
+			->where($query->expr()->eq('command', $query->createNamedParameter($cmd)));
+
+		if ($app === '') {
+			$query->andWhere($query->expr()->emptyString('app'));
+		} else {
+			$query->andWhere($query->expr()->eq('app', $query->createNamedParameter($app)));
+		}
 
 		return $this->findEntity($query);
 	}
diff --git a/lib/Model/SelectHelper.php b/lib/Model/SelectHelper.php
new file mode 100644
index 00000000000..48973cacc36
--- /dev/null
+++ b/lib/Model/SelectHelper.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2020 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Talk\Model;
+
+use OCP\DB\QueryBuilder\IQueryBuilder;
+
+class SelectHelper {
+	public function selectRoomsTable(IQueryBuilder $query, string $alias = 'r'): void {
+		if ($alias !== '') {
+			$alias .= '.';
+		}
+
+		$query->addSelect($alias . 'type')
+			->addSelect($alias . 'read_only')
+			->addSelect($alias . 'lobby_state')
+			->addSelect($alias . 'sip_enabled')
+			->addSelect($alias . 'assigned_hpb')
+			->addSelect($alias . 'token')
+			->addSelect($alias . 'name')
+			->addSelect($alias . 'description')
+			->addSelect($alias . 'password')
+			->addSelect($alias . 'active_guests')
+			->addSelect($alias . 'active_since')
+			->addSelect($alias . 'last_activity')
+			->addSelect($alias . 'last_message')
+			->addSelect($alias . 'lobby_timer')
+			->addSelect($alias . 'object_type')
+			->addSelect($alias . 'object_id')
+			->addSelect($alias . 'listable')
+			->selectAlias($alias . 'id', 'r_id');
+	}
+
+	public function selectAttendeesTable(IQueryBuilder $query, string $alias = 'a'): void {
+		if ($alias !== '') {
+			$alias .= '.';
+		}
+
+		$query->addSelect($alias . 'room_id')
+			->addSelect($alias . 'actor_type')
+			->addSelect($alias . 'actor_id')
+			->addSelect($alias . 'display_name')
+			->addSelect($alias . 'pin')
+			->addSelect($alias . 'participant_type')
+			->addSelect($alias . 'favorite')
+			->addSelect($alias . 'notification_level')
+			->addSelect($alias . 'last_joined_call')
+			->addSelect($alias . 'last_read_message')
+			->addSelect($alias . 'last_mention_message')
+			->addSelect($alias . 'read_privacy')
+			->selectAlias($alias . 'id', 'a_id');
+	}
+
+	public function selectSessionsTable(IQueryBuilder $query, string $alias = 's'): void {
+		if ($alias !== '') {
+			$alias .= '.';
+		}
+
+		$query->addSelect($alias . 'attendee_id')
+			->addSelect($alias . 'session_id')
+			->addSelect($alias . 'in_call')
+			->addSelect($alias . 'last_ping')
+			->selectAlias($alias . 'id', 's_id');
+	}
+}
diff --git a/lib/Room.php b/lib/Room.php
index e371631c5be..6943e69d56c 100644
--- a/lib/Room.php
+++ b/lib/Room.php
@@ -34,6 +34,7 @@
 use OCA\Talk\Events\VerifyRoomPasswordEvent;
 use OCA\Talk\Exceptions\ParticipantNotFoundException;
 use OCA\Talk\Model\Attendee;
+use OCA\Talk\Model\SelectHelper;
 use OCA\Talk\Service\ParticipantService;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Comments\IComment;
@@ -402,10 +403,10 @@ public function getParticipant(?string $userId): Participant {
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin('a', 'talk_sessions', 's', $query->expr()->eq('a.id', 's.attendee_id'))
 			->where($query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_USERS)))
 			->andWhere($query->expr()->eq('a.actor_id', $query->createNamedParameter($userId)))
@@ -438,10 +439,10 @@ public function getParticipantBySession(?string $sessionId): Participant {
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_sessions', 's')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_sessions', 's')
 			->leftJoin('s', 'talk_attendees', 'a', $query->expr()->eq('a.id', 's.attendee_id'))
 			->where($query->expr()->eq('s.session_id', $query->createNamedParameter($sessionId)))
 			->andWhere($query->expr()->eq('a.room_id', $query->createNamedParameter($this->getId())))
@@ -464,10 +465,10 @@ public function getParticipantBySession(?string $sessionId): Participant {
 	 */
 	public function getParticipantByPin(string $pin): Participant {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin('a', 'talk_sessions', 's', $query->expr()->eq('a.id', 's.attendee_id'))
 			->andWhere($query->expr()->eq('a.pin', $query->createNamedParameter($pin)))
 			->andWhere($query->expr()->eq('a.room_id', $query->createNamedParameter($this->getId())))
@@ -490,10 +491,10 @@ public function getParticipantByPin(string $pin): Participant {
 	 */
 	public function getParticipantByAttendeeId(int $attendeeId): Participant {
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin('a', 'talk_sessions', 's', $query->expr()->eq('a.id', 's.attendee_id'))
 			->andWhere($query->expr()->eq('a.id', $query->createNamedParameter($attendeeId, IQueryBuilder::PARAM_INT)))
 			->andWhere($query->expr()->eq('a.room_id', $query->createNamedParameter($this->getId())))
@@ -521,10 +522,10 @@ public function getParticipantByActor(string $actorType, string $actorId): Parti
 		}
 
 		$query = $this->db->getQueryBuilder();
-		$query->select('*')
-			->selectAlias('a.id', 'a_id')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin('a', 'talk_sessions', 's', $query->expr()->eq('a.id', 's.attendee_id'))
 			->andWhere($query->expr()->eq('a.actor_type', $query->createNamedParameter($actorType)))
 			->andWhere($query->expr()->eq('a.actor_id', $query->createNamedParameter($actorId)))
diff --git a/lib/Service/CommandService.php b/lib/Service/CommandService.php
index a6b732a6c94..1c43f77ca57 100644
--- a/lib/Service/CommandService.php
+++ b/lib/Service/CommandService.php
@@ -97,9 +97,6 @@ public function updateFromWeb(int $id, int $response, int $enabled): Command {
 	 */
 	public function update(int $id, string $cmd, string $name, string $script, int $response, int $enabled): Command {
 		$command = $this->mapper->findById($id);
-		if ($command->getApp() !== '' || $command->getCommand() === 'help') {
-			throw new \InvalidArgumentException('app', 0);
-		}
 
 		$command->setName($name);
 		$command->setScript($script);
@@ -141,7 +138,7 @@ protected function validateCommand(Command $command): void {
 				} catch (DoesNotExistException $e) {
 					throw new \InvalidArgumentException('script', 3);
 				}
-			} else {
+			} elseif ($script !== 'help') {
 				if (preg_match('/[`\'"]{(?:ARGUMENTS|ROOM|USER)}[`\'"]/i', $script)) {
 					throw new \InvalidArgumentException('script-parameters', 6);
 				}
diff --git a/lib/Service/ParticipantService.php b/lib/Service/ParticipantService.php
index c7975cc752c..cf78aff277a 100644
--- a/lib/Service/ParticipantService.php
+++ b/lib/Service/ParticipantService.php
@@ -37,6 +37,7 @@
 use OCA\Talk\Exceptions\UnauthorizedException;
 use OCA\Talk\Model\Attendee;
 use OCA\Talk\Model\AttendeeMapper;
+use OCA\Talk\Model\SelectHelper;
 use OCA\Talk\Model\Session;
 use OCA\Talk\Model\SessionMapper;
 use OCA\Talk\Participant;
@@ -447,8 +448,9 @@ public function cleanGuestParticipants(Room $room): void {
 		$this->sessionService->deleteSessionsById($sessionTableIds);
 
 		$query = $this->connection->getQueryBuilder();
-		$query->selectAlias('a.id', 'a_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin('a', 'talk_sessions', 's', $query->expr()->eq('s.attendee_id', 'a.id'))
 			->where($query->expr()->eq('a.room_id', $query->createNamedParameter($room->getId(), IQueryBuilder::PARAM_INT)))
 			->andWhere($query->expr()->eq('a.actor_type', $query->createNamedParameter(Attendee::ACTOR_GUESTS)))
@@ -561,11 +563,10 @@ public function getLastCommonReadChatMessageForMultipleRooms(array $roomIds): ar
 	public function getParticipantsForRoom(Room $room): array {
 		$query = $this->connection->getQueryBuilder();
 
-		$query->select('a.*')
-			->selectAlias('a.id', 'a_id')
-			->addSelect('s.*')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin(
 				'a', 'talk_sessions', 's',
 				$query->expr()->eq('s.attendee_id', 'a.id')
@@ -582,11 +583,10 @@ public function getParticipantsForRoom(Room $room): array {
 	public function getParticipantsWithSession(Room $room): array {
 		$query = $this->connection->getQueryBuilder();
 
-		$query->select('a.*')
-			->selectAlias('a.id', 'a_id')
-			->addSelect('s.*')
-			->selectAlias('s.id', 's_id')
-			->from('talk_attendees', 'a')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_attendees', 'a')
 			->leftJoin(
 				'a', 'talk_sessions', 's',
 				$query->expr()->eq('s.attendee_id', 'a.id')
@@ -604,11 +604,10 @@ public function getParticipantsWithSession(Room $room): array {
 	public function getParticipantsInCall(Room $room): array {
 		$query = $this->connection->getQueryBuilder();
 
-		$query->select('a.*')
-			->selectAlias('a.id', 'a_id')
-			->addSelect('s.*')
-			->selectAlias('s.id', 's_id')
-			->from('talk_sessions', 's')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_sessions', 's')
 			->leftJoin(
 				's', 'talk_attendees', 'a',
 				$query->expr()->eq('s.attendee_id', 'a.id')
@@ -627,11 +626,10 @@ public function getParticipantsInCall(Room $room): array {
 	public function getParticipantsByNotificationLevel(Room $room, int $notificationLevel): array {
 		$query = $this->connection->getQueryBuilder();
 
-		$query->select('a.*')
-			->selectAlias('a.id', 'a_id')
-			->addSelect('s.*')
-			->selectAlias('s.id', 's_id')
-			->from('talk_sessions', 's')
+		$helper = new SelectHelper();
+		$helper->selectAttendeesTable($query);
+		$helper->selectSessionsTable($query);
+		$query->from('talk_sessions', 's')
 			->leftJoin(
 				's', 'talk_attendees', 'a',
 				$query->expr()->eq('s.attendee_id', 'a.id')