diff --git a/include/class-QueryAppUser.php b/include/class-QueryAppUser.php
index f4b84cc..440b5c9 100644
--- a/include/class-QueryAppUser.php
+++ b/include/class-QueryAppUser.php
@@ -1,41 +1,55 @@
 <?php
 # WikiCAPTCHA Control Room
 # Copyright (C) 2019 Valerio Bozzolan and contributors
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU 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 General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 /**
  * Execute a Query against the 'appuser' table
  */
-class QueryAppUser {
+class QueryAppUser extends Query {
 
-	use AppTrait;
-	use UserTrait;
+	use QueryAppTrait;
+	use QueryUserTrait;
+
+	/**
+	 * Univoque User ID column name
+	 *
+	 * @var string
+	 */
+	protected $USER_ID = 'appuser.user_ID';
+
+	/**
+	 * Univoque App ID column name
+	 *
+	 * @var string
+	 */
+	protected $APP_ID = 'app.app_ID';
 
 	/**
 	 * Constructor
 	 *
 	 * @param object $db         Database connection
 	 * @param string $class_name Default class name for the results
 	 */
 	public function __construct( $db = null, $class_name = 'Queried' ) {
 
 		// set the database connection and the default class name for the results
 		parent::__construct( $db, $class_name );
 
 		// set FROM table
 		$this->from( 'appuser' );
 	}
 
 }