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,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)

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

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;

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

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=new.gid;

使用mydb7 openlab库

4、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 (0.01 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 |
+------+----------+

5、创建存储过程s2，实现输入员工姓名后返回员工的年龄

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('张三',@age);
Query OK, 1 row affected (0.00 sec)

mysql> select @age;
+------+
| @age |
+------+
|   35 |
+------+

6、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> 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 //
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       |
+----------------+
| 3166.669921875 |
+----------------+
1 row in set (0.00 sec)