find chat user rooms stored procedure

drop procedure if exists find_chat_user_rooms;

DELIMITER //

CREATE PROCEDURE find_chat_user_rooms(IN chat_user_id INT(10))
  BEGIN
    SELECT id FROM chat_room WHERE author_id = chat_user_id
    UNION SELECT rooms_from_users_id FROM chat_room_users WHERE users_id = chat_user_id;
  END;

DELIMITER ;

CALL find_chat_user_rooms(583);