MySQL触发器和存储过程

一.触发器

1.建立触发器，订单表中增加订单数量后，商品表商品数量同步减少对应的商品订单出数量

USE mydb7_openlab;
DELIMITER //
CREATE TRIGGER one
AFTER INSERT ON orders
FOR EACH ROW
BEGIN
    UPDATE goods
    SET num = num - NEW.onum
    WHERE gid = NEW.gid;
END //
DELIMITER ;

2.建立触发器，实现功能：客户取消订单，恢复商品表对应商品的数量

USE mydb7_openlab;
DELIMITER //
CREATE TRIGGER two
AFTER DELETE ON orders
FOR EACH ROW
BEGIN
    UPDATE goods
    SET num = num + OLD.onum
    WHERE gid = OLD.gid;
END //
DELIMITER ;

3.建立触发器，实现功能：客户修改订单，商品表对应商品数量同步更新

USE mydb7_openlab;
DELIMITER //
CREATE TRIGGER three
AFTER UPDATE ON orders
FOR EACH ROW
BEGIN
    UP