题目
1、换库并建表
mysql> use mydb16_trigger;
Database changed
mysql>
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>
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 (0.04 sec)
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 (0.02 sec)
Records: 4 Duplicates: 0 Warnings: 0
2、触发器的设置
2.1 在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> select * from orders;
Empty set (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> insert into orders (gid,name,price,onum,otime) values ('C0001','铅笔'
,1.2,80,now());
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> select * from orders;
+
| oid | gid | name | price | onum | otime |
+
| 1 | C0001 | 铅笔 | 1.20 | 80 | 2025-02-10 |
+
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)
2.2 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 (0.02 sec)
mysql> delete from orders where gid='C0001';
Query OK, 1 row affected (0.00 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)
2.3 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> 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> select * from orders;
+
| oid | gid | name | price | onum | otime |
+
| 10002 | b0001 | 小楷本 | 2.80 | 30 | 2025-02-10 |
+
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 | 180 |
| c0001 | 铅笔 | 1.20 | 120 |
| d0001 | 计算器 | 28.00 | 20 |
+
4 rows in set (0.00 sec)
mysql> update orders set onum=50 where gid='b0001';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from orders;
+
| oid | gid | name | price | onum | otime |
+
| 10002 | b0001 | 小楷本 | 2.80 | 50 | 2025-02-10 |
+
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 | 160 |
| c0001 | 铅笔 | 1.20 | 120 |
| d0001 | 计算器 | 28.00 | 20 |
+
4 rows in set (0.00 sec)
3、存储过程
3.1 创建提取emp_new表所有员工姓名和工资的存储过程s1
mysql> use mydb7_openlab
Database changed
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 (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
3.2 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 (0.02 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)
3.3 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 out_avg_sal double)
-> begin
-> select round(avg(incoming),2) into out_avg_sal from emp_new where dept2=in_dept group by dept2;
-> end
Query OK, 0 rows affected (0.02 sec)
mysql> delimiter ;
mysql> call s3(101,@avg_sal);
Query OK, 1 row affected (0.00 sec)
mysql> select @avg_sal;
+
| @avg_sal |
+
| 3166.67 |
+
1 row in set (0.00 sec)
