Mine

    /**     * Count the users in room     *      * @param  string roomId     * @return int    the count of users     *      * @global Db     */    public function countUsersInRoom($roomId) {        global $Db;        $Db->execute(            'SELECT COUNT(*) AS count ' .            'FROM chatdata, usersinrooms ' .            'WHERE chatdata.ischatting=1 AND chatdata.uid!=0 AND usersinrooms.room=%s ' .            'AND usersinrooms.id=chatdata.uid AND usersinrooms.id!=0',            $roomId        );        $tmpCount = $Db->fields[0]['count'];        $Db->execute('SELECT id FROM chatrooms WHERE p_id=%u', $roomId);        $fields = $Db->fields;        for ($i = 0, $max = $Db->recordCount(); $i < $max; $i++) {            $Db->execute(                'SELECT COUNT(*) AS count ' .                'FROM chatdata, usersinrooms ' .                'WHERE chatdata.ischatting=1 AND usersinrooms.room=%s AND usersinrooms.id=chatdata.uid AND uid!=0',                $fields[$i]['id']            );            $tmpCount += $Db->fields[0]['count'];        }                return $tmpCount;    }