创建触发器

题目

创建一个触发器当订单表中新增一条订单，商品列表中相对应的商品库存随之减少

DELIMITER $$

CREATE TRIGGER order_add AFTER INSERT ON orders FOR EACH ROW

BEGIN

UPDATE goods SET goods.num = goods.num - new.num WHERE goods.g_name = new.g_name;

END $$
DELIMITER;

创建一个触发器当订单表中商品数量更新率，要求商品表中库存随之更新

DELIMITER $$

CREATE TRIGGER order_update AFTER UPDATE ON orders FOR EACH ROW

BEGIN

UPDATE goods SET goods.num = goods.num - (new.num - old.num) WHERE goods.g_name = new.g_name;

END $$
DELIMITER;