Вот так все выглядит MySQL Query Browser:

DELIMITER $$

DROP PROCEDURE IF EXISTS `add_order_cast` $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `add_order_cast`(order_id$ int, menu_id$ int, reg_id$ int, quant$ int)
BEGIN
declare menu_price$ int;
SELECT price*quant$ into menu_price$ FROM menu_price where menu_id = menu_id$ and reg_id = reg_id$;
insert into order_cast(order_id, menu_id, quant, cost) values (order_id$, menu_id$, quant$, menu_price$);
END $$

DELIMITER ;