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MySql 触发器、存储器练习

news 2025/7/19 18:38:14

一：触发器

1、建立两个表:goods(商品表)、orders(订单表)

查看数据库：mysql> show databases;

使用数据库：mysql> use mydb16_trigger;

创建goods表：

mysql> create table goods(gid char(8) not null primary key, name varchar(10),price decimal(8,2),num int);

查看表结构：mysql> desc goods;

创建orders表：

mysql> create table orders(oid int not null primary key auto_increment,
-> gid char(10) not null,name varchar(10),
-> price decimal(8,2), onum int, otime date);

查看表结构：mysql> desc orders;

2、插入数据

mysql> insert into goods values('A0001','橡皮',2.5,100),('B0001','小楷本',2.8,210), ('C0001','铅笔',1.2,120), ('D0001','计算器',28,20);

查看数据：mysql> select * from goods;

3、建立触发器

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,并测试

mysql> create trigger orders_after_insert_trigger
-> after insert on orders for each row
-> update goods set num=num-new.onum
-> where gid=new.gid;

mysql> insert into orders(gid,name,price,onum,otime) values('A0001','橡皮',2.5,20,now());

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

mysql> create trigger orders_after_delete_trigger
-> after delete on orders for each row
-> update goods set num=num+old.onum
-> where gid=old.gid;
mysql> delete from orders where gid='A0001';

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

mysql> create trigger orders_after_update_trigger
-> after update on orders for each row
-> update goods set num=num+(old.onum-new.onum)
-> where gid=old.gid;

mysql> update orders set onum=70 where gid='A0001';

二：存储过程

1、使用mydb7 openlab库

使用数据库：mysql> use mydb7_openlab;

查看表：mysql> show tables;

查看emp_new表

查看dept表

2、创建提取emp_new表所有员工姓名和工资的存储过程s1

修改结束符号：mysql> delimiter //

mysql> create procedure s1()
-> begin
-> select name,incoming from emp_new;
-> end //

mysql> delimiter ;

调用：call s1();

3、创建存储过程s2，实现输入员工姓名后返回员工的年龄

mysql> delimiter //

mysql> create procedure s2(in in_name varchar(11), out out_age int)
-> begin
-> select age into out_age from emp_new where name=in_name;
-> end //

mysql> delimiter ;

mysql> call s2('牛八',@age);

mysql> select * from emp_new;

mysql> select @age;

4、创建一个存储过程s3，有2个参数，传入部门号，返回该部门的平均工资

mysql> delimiter //

mysql> create procedure s3(in in_dept int, out avg_sal float)
-> begin
-> select avg(incoming) into avg_sal from emp_new where dept2=in_dept;
-> end //

mysql> delimiter ;

mysql> call s3(101,@avg_sal);

mysql> select @avg_sal;