1、触发器
建立两个表:goods(商品表)、orders(订单表)
mysql> use mydb16_trigger;
Database changed
mysql> create table goods
-> (
-> gid char(8) primary key,
-> name varchar(10),
-> price decimal(8,2),
-> num int
-> );
Query OK, 0 rows affected (0.04 sec)
mysql> create table orders
-> (
-> oid int primary key auto_increment,
-> gid char(10) not null,
-> name varchar(10),
-> price decimal(8,2),
-> onum int,
-> otime date
-> );
Query OK, 0 rows affected (0.03 sec)
mysql> desc goods;
+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| gid | char(8) | NO | PRI | NULL | |
| name | varchar(10) | YES | | NULL | |
| price | decimal(8,2) | YES | | NULL | |
| num | int | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
mysql> desc orders;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| oid | int | NO | PRI | NULL | auto_increment |
| gid | char(10) | NO | | NULL | |
| name | varchar(10) | YES | | NULL | |
| price | decimal(8,2) | YES | | NULL | |
| onum | int | YES | | NULL | |
| otime | date | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)
在商品表中导入商品记录
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);
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 100 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 120 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
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;
Query OK, 0 rows affected (0.01 sec)
mysql> insert into orders(gid,name,price,onum,otime) value('C0001', '铅笔', 1.2,80,now());
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 100 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 40 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
mysql> select * from orders;
+-----+-------+------+-------+------+------------+
| oid | gid | name | price | onum | otime |
+-----+-------+------+-------+------+------------+
| 1 | C0001 | 铅笔 | 1.20 | 80 | 2024-07-25 |
+-----+-------+------+-------+------+------------+
1 row in set (0.00 sec)
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;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from orders;
+-----+-------+------+-------+------+------------+
| oid | gid | name | price | onum | otime |
+-----+-------+------+-------+------+------------+
| 1 | C0001 | 铅笔 | 1.20 | 80 | 2024-07-25 |
+-----+-------+------+-------+------+------------+
1 row in set (0.00 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 100 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 40 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
mysql> delete from orders where gid='C0001';
Query OK, 1 row affected (0.01 sec)
mysql> select * from orders;
Empty set (0.00 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 100 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 120 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
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;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 100 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 120 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
mysql> select * from orders;
Empty set (0.00 sec)
mysql> insert into orders(gid,name,price,onum,otime) value('A0001','橡皮',2.5,20,now());
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 80 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 120 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
mysql> select * from orders;
+-----+-------+------+-------+------+------------+
| oid | gid | name | price | onum | otime |
+-----+-------+------+-------+------+------------+
| 2 | A0001 | 橡皮 | 2.50 | 20 | 2024-07-25 |
+-----+-------+------+-------+------+------------+
1 row in set (0.00 sec)
mysql> update orders set onum=35 where gid='A0001';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from orders;
+-----+-------+------+-------+------+------------+
| oid | gid | name | price | onum | otime |
+-----+-------+------+-------+------+------------+
| 2 | A0001 | 橡皮 | 2.50 | 35 | 2024-07-25 |
+-----+-------+------+-------+------+------------+
1 row in set (0.00 sec)
mysql> select * from goods;
+-------+--------+-------+------+
| gid | name | price | num |
+-------+--------+-------+------+
| A0001 | 橡皮 | 2.50 | 65 |
| B0001 | 小楷本 | 2.80 | 210 |
| C0001 | 铅笔 | 1.20 | 120 |
| D0001 | 计算器 | 28.00 | 20 |
+-------+--------+-------+------+
4 rows in set (0.00 sec)
2、存储过程
使用mydb7 openlab库
mysql> use mydb7_openlab
Database changed
创建提取emp_new表所有员工姓名和工资的存储过程s1
mysql> delimiter $$
mysql> create procedure s1()
-> begin
-> select name,incoming from emp_new;
-> end $$
Query OK, 0 rows affected (0.02 sec)
mysql> delimiter ;
mysql> call s1();
+------+----------+
| name | incoming |
+------+----------+
| 张三 | 4000 |
| 李四 | 3500 |
| 王五 | 2000 |
| 赵六 | 7500 |
| 荣七 | 8500 |
| 牛八 | 7300 |
+------+----------+
6 rows in set (0.01 sec)
Query OK, 0 rows affected (0.03 sec)
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 $$
mysql> create procedure s2(in in_name varchar(11), out out_age int)
-> begin
-> select age into out_age from emp_new where name=in_name;
-> end $$
Query OK, 0 rows affected (0.01 sec)
mysql> delimiter ;
mysql> call s2('赵六',@age);
Query OK, 1 row affected (0.00 sec)
mysql> select @age;
+------+
| @age |
+------+
| 57 |
+------+
1 row in set (0.00 sec)
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 $$
mysql> create procedure s3(in in_dept int, out avg_sal float)
-> begin
-> select avg(incoming) into avg_sal from emp_new
-> where dept2=in_dept group by dept2;
-> end $$
Query OK, 0 rows affected (0.01 sec)
mysql> delimiter ;
mysql> call s3(101,@avg_sal);
Query OK, 1 row affected (0.00 sec)
mysql> select @avg_sal;
+-------------------+
| @avg_sal |
+-------------------+
| 3166.666748046875 |
+-------------------+
1 row in set (0.00 sec)