¿Consultando campos separados por comas?

En caso de que realmente necesite ordenarlo ahora sin rediseñar su base de datos (que yo haría)...

$ids = array(1,2,4);

$query = "SELECT room_location.*, client_room.*, users.* FROM room_location INNER JOIN client_room ON room_location.user_loc_id = client_room.id INNER JOIN users ON room_location.user_loc_id = users.userGroupLocID WHERE userGroupLocID REGEXP '(^|,)(".implode('|',$ids).")(,|$)' ORDER BY room_location.location";