Mysql作业5 - 技术栈

一、触发器

1、建立两个表:goods (商品表)、orders(订单表)

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mysql> create database mydb16_trigger;

mysql> use mydb16_trigger;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

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 (0.02 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 (0.02 sec)

2、在商品表中导入商品记录

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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','计算机',28,20);

3、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测试

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mysql> delimiter //
mysql> create trigger trg_order_insert 
    -> after insert on orders for each row
    -> begin
    -> update goods set num = num - new.onum where gid = new.gid;
    -> end //
mysql> delimiter ;
mysql> insert into orders (gid, name, price, onum, otime)
    -> values ('a0001', '橡皮', 2.50, 10, '2025-11-07 10:00:00');
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> select * from goods where gid = 'a0001';
+-------+--------+-------+------+
| gid   | name   | price | num  |
+-------+--------+-------+------+
| A0001 | 橡皮   |  2.50 |   90 |
+-------+--------+-------+------+
1 row in set (0.00 sec)

4、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

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mysql> delimiter //
mysql> create trigger trg_order_delete 
    -> after delete on orders for each row
    -> begin
    ->     update goods set num = num + old.onum where gid = old.gid;
    -> end //
Query OK, 0 rows affected (0.01 sec)

mysql> delimiter ;
mysql> delete from orders where oid = 1;
Query OK, 1 row affected (0.00 sec)

mysql> select * from goods where gid = 'a0001';
+-------+--------+-------+------+
| gid   | name   | price | num  |
+-------+--------+-------+------+
| A0001 | 橡皮   |  2.50 |   100 |
+-------+--------+-------+------+
1 row in set (0.00 sec)

5、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

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mysql> delimiter //
mysql> create trigger trg_order_update 
    -> after update on orders for each row
    -> begin
    ->     update goods set num = num + old.onum where gid = old.gid;
    ->     update goods set num = num - new.onum where gid = new.gid;
    -> end //
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> insert into orders (gid, name, price, onum, otime)
    -> values ('C0001', '铅笔', 1.2, 10, '2025-11-07 11:00:00');
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> update orders set onum = 5 where oid = 2;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> select * from goods where gid = 'C0001';
+-------+--------+-------+------+
| gid   | name   | price | num  |
+-------+--------+-------+------+
| C0001 | 铅笔   |  1.20 |  110 |
+-------+--------+-------+------+
1 row in set (0.01 sec)

二、存储过程

1、使用mydb7.openlab库；

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mysql> use mydb7_openlab;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select * from emp_new;
+------+--------+------+----------------+----------+-------+
| sid  | name   | age  | worktime_start | incoming | dept2 |
+------+--------+------+----------------+----------+-------+
| 1789 | 张三   |   35 | 1980-01-01     |     4000 |   101 |
| 1674 | 李四   |   32 | 1983-04-01     |     3500 |   101 |
| 1776 | 王五   |   24 | 1990-07-01     |     2000 |   101 |
| 1568 | 赵六   |   57 | 1970-10-11     |     7500 |   102 |
| 1564 | 荣七   |   64 | 1963-10-11     |     8500 |   102 |
| 1879 | 牛八   |   55 | 1971-10-20     |     7300 |   103 |
+------+--------+------+----------------+----------+-------+
6 rows in set (0.01 sec)

2、创建提取emp_new表所有员工姓名和工资的存储过程s1；

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mysql> delimiter //
mysql> create procedure s1()
    -> begin
    ->     select name, incoming from emp_new;
    -> end //
Query OK, 0 rows affected (0.00 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 (0.00 sec)

3、创建存储过程s2，实现输入员工姓名后返回员工的年龄；

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mysql> delimiter //
mysql> create procedure s2()
    -> begin
    ->     select name, age from emp_new;
    -> end //
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> call s2();
+--------+------+
| name   | age  |
+--------+------+
| 张三   |   35 |
| 李四   |   32 |
| 王五   |   24 |
| 赵六   |   57 |
| 荣七   |   64 |
| 牛八   |   55 |
+--------+------+
6 rows in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

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。

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mysql> delimiter $$
mysql> create procedure s3(in dept_no int, out avg_sal decimal(10,2))
    -> begin
    ->     select avg(incoming) into avg_sal from emp_new where dept2 = dept_no;
    -> end $$
set @avg=0;
call s3(101, @avg);
select @avg; 
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
Query OK, 0 rows affected (0.00 sec)

mysql> set @avg=0;
Query OK, 0 rows affected (0.00 sec)

mysql> call s3(101, @avg);
Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> select @avg; 
+---------+
| @avg    |
+---------+
| 3166.67 |
+---------+
1 row in set (0.00 sec)