SQL-INSERT触发器练习

&练习一

有这样的一个基础表A，字段包括：id、type、value、create_time，主要是记录某个类型的状态变化时间和值。在插入类型（type）为‘runtime’ 的数据时，根据前后变化的值，更新一条该type的前后两条时间组合的信息到另一张表B。

定义：value为布尔型，true-->false时，为停止时间，false-->true时，为运行时间

具体要求：表A插入一条runstate的数据时，需要在表B插入一条停止或运行的信息。

eg：

A表

B表

触发器如下（如有问题，欢迎指出）：

 1 CREATE TRIGGER RUN_STATE

 2 ON A

 3 FOR INSERT

 4 AS

 5     IF( (SELECT COUNT(1) FROM inserted) > 1 )

 6     BEGIN

 7         RAISERROR('一次只能插入一条数据！',16,10);

 8         rollback;

 9     END

10     ELSE

11     BEGIN

12         IF( (SELECT TOP 1 type FROM inserted)='runtime' ) ----插入的数据是否为runtime状态信息

13         BEGIN

14             IF EXISTS ( SELECT 1 FROM B WHERE type = 'runtime') -----B表中是否已经创建了runtime信息表

15             BEGIN

16                 DECLARE @Old_state varchar(10),@create_time smalldatetime;

17                 SET @Old_state = (SELECT state FROM B WHERE type = 'runtime');

18                 SET @Create_time = (SELECT TOP 1 create_time FROM inserted);

19                 if @Old_state = '运行'

20                     BEGIN

21                     update B SET end_time = @Create_time WHERE type = 'runtime';

22                     update B SET state = @Create_time WHERE type = '停止';

23                     END

24                 ELSE

25                     BEGIN

26                     update B SET start_time = @Create_time WHERE type = 'runtime';

27                     update B SET state = @Create_time WHERE type = '运行';

28                     END

29             END

30             else

31             BEGIN

32                 DECLARE @id int,@type varchar(20),@value bit;

33                 SELECT TOP 1 @id=id,@type=type,@value=value,@create_time=create_time FROM inserted;

34                 IF @value = 1

35                     INSERT B (id,type,start_time,state) values(@id,'runtime',@create_time,'运行');

36                 ELSE

37                     INSERT B (id,type,end_time,state) values(@id,'runtime',@create_time,'停止');

38             END

39         END

40     END

41 GO

&练习二

需要用到的表如下（卷烟库存表【CI_list】，卷烟销售表【CS_list】）：

--业务规则：库存金额 = 库存数量 * 库存单价

--业务规则：销售金额 = 销售数量 * 销售单价

eg1：强制执行业务规则，保证插入的数据中，库存金额 = 库存数量 * 库存单价，且库存金额不为空

触发器如下（如有问题，欢迎指出）：

 1 CREATE TRIGGER T_INSERT_CS

 2 ON CS_list

 3 FOR INSERT

 4 AS

 5 DECLARE @i_num int,@i_uprice money,@i_amount money;

 6 IF ( (SELECT COUNT(*) FROM inserted)>1 )

 7 BEGIN

 8     RAISERROR('一次只能插入一行数据',16,10);

 9     ROLLBACK;

10 END

11 ELSE

12 BEGIN

13     SELECT TOP 1 @i_num=i_num,@i_uprice=i_uprice,@i_amount=i_amount FROM inserted;

14     IF ISNULL(@i_amount,1)=1 OR @i_amount != @i_num*@i_uprice

15     BEGIN

16         RAISERROR('插入的数据不符合业务规则！已根据规则修改数据',16,10);

17         UPDATE CS_list SET i_amount = @i_num*@i_uprice WHERE cs_brand IN (SELECT TOP 1 cs_brand FROM inserted)

18     END

19 END

20 GO

21

22 INSERT INTO CS_list values('红塔山新势力',2,30,60);

23 INSERT INTO CS_list (cs_brand,i_num,i_uprice) values('红1',2,20);

24 INSERT INTO CS_list values('云南映像',2,30,70);

25 GO

eg2：如果销售的卷烟品牌不存在库存或者库存为零，则返回错误；否则则自动减少[卷烟库存表]中对应品牌卷烟的库存数量和库存金额。并且满足业务规则

触发器如下（如有问题，欢迎指出）：

 1 CREATE TRIGGER T_INSERT_CI

 2 ON CI_list

 3 FOR INSERT

 4 AS

 5 IF ( (SELECT COUNT(*) FROM inserted)>1 )

 6 BEGIN

 7     RAISERROR('一次只能插入一行数据',16,10);

 8     ROLLBACK;

 9 END

10 ELSE

11 BEGIN

12     DECLARE @CI_BRAND varchar(40),@CS_BRAND varchar(40);

13     DECLARE @s_num int,@s_uprice money,@s_amount money;

14     SELECT TOP 1 @CI_BRAND=ci_brand,@s_num=s_num,@s_uprice=s_uprice,@s_amount=s_amount FROM inserted;

15     IF not EXISTS (SELECT 1 FROM CS_list WHERE cs_brand=@CI_BRAND)

16     BEGIN17         RAISERROR('库存中不含当前要销售的卷烟',16,10);

18         ROLLBACK;

19     END

20     ELSE IF (SELECT i_num FROM CS_list WHERE cs_brand=@CI_BRAND) = 0

21     BEGIN

22         RAISERROR('库存中已经没有当前要销售的香烟',16,10);

23         ROLLBACK;

24     END

25     ELSE

26     BEGIN

27         IF ISNULL(@s_amount,1)=1 OR @s_amount != @s_num*@s_uprice

28         BEGIN

29             RAISERROR('插入的数据不符合业务规则！已根据规则修改数据',16,10);

30             UPDATE CI_list SET s_amount = @s_num*@s_uprice WHERE ci_brand = (SELECT TOP 1 ci_brand FROM inserted)

31         END

32         UPDATE CS_list SET i_num=i_num-@s_num WHERE cs_brand = (SELECT TOP 1 ci_brand FROM inserted);

33         UPDATE CS_list SET i_amount=i_num*i_uprice WHERE cs_brand = (SELECT TOP 1 ci_brand FROM inserted);

34     END

35 END

&练习三

如下所示三张表（ student，grade，student_updata_before ）：

student表

grade表

Student_update_before表

触发器需要实现一下要求：

如果学生所在的班级存在，则班级表学生数+1。
如果学生所在的班级不存在，则在班级表中新建班级，并将该学生加入到该班级中。

触发器如下（如有问题，欢迎指出）：

 1 CREATE TRIGGER Add_stu

 2 ON student

 3 FOR INSERT

 4 AS

 5 IF ( SELECT COUNT(1) FROM inserted ) > 1

 6 BEGIN

 7     RAISERROR('每次只能插入一条数据',16,10);

 8     ROLLBACK;

 9 END

10 ELSE

11 BEGIN

12     DECLARE @Sg_name varchar(30);

13     SELECT TOP 1 @Sg_name = Sg_name FROM inserted;

14     IF EXISTS ( SELECT 1 FROM grade WHERE Gname = @Sg_name )

15     BEGIN

16         DECLARE @num1 int;

17         SET @num1 = (SELECT COUNT(*) FROM student WHERE Sg_name = @Sg_name);

18         UPDATE grade SET Gnum = @num1 WHERE Gname = @Sg_name;

19     END

20     ELSE

21     BEGIN

22         DECLARE @gid int;

23         IF (SELECT COUNT(1) FROM grade) = 0

24             SET @gid = 1;

25         ELSE

26             SET @gid = (SELECT MAX(Gid) FROM grade ) + 1;

27         declare @num int;

28         INSERT INTO grade VALUES(@gid,@Sg_name,1,'');

29     END

30 END

31 GO

&练习四

#准备工作：创建员工employee表、部门变动历史dept_history表，工资变动历史sal_history表

#1,创建员工employee表:

1 CREATE TABLE employee(

2     eid varchar(20) PRIMARY KEY,

3     ename varchar(20),

4     dept varchar(20),

5     salary int,

6     uptime date,

7     status int

8 )

9 go

#2,创建部门变动历史dept_history表

CREATE TABLE dept_history(

    did int identity(1,1) primary key,

    eid varchar(20),

    olddept varchar(20),

    newdept varchar(20),

    uptime date,

    FOREIGN KEY(eid) REFERENCES employee(eid)

)

go

#3，创建工资变动历史sal_history表

1 CREATE TABLE sal_history(

2     sid int identity(1,1) primary key,

3     eid varchar(20),

4     oldsal varchar(20),

5     newsal varchar(20),

6     uptime date,

7     FOREIGN KEY(eid) REFERENCES employee(eid)

8 )

9 go

触发器实现功能：当新职工入职时，员工信息表将插入1条数据。同时，触发器在部门变动历史中增加1条记录，其中olddept值为null；在工资变动历史中增加1条记录，其中oldsal值为0。

触发器如下（如有问题，欢迎指出）：

CREATE TRIGGER Add_em

ON employee

FOR INSERT

AS

IF ( SELECT COUNT(1) FROM inserted ) > 1

BEGIN

    RAISERROR('每次只能插入一条数据！请重新输入！',16,10)

END

ELSE

BEGIN

    DECLARE @eid varchar(20),@dept varchar(20),@salary int;

    SELECT TOP 1 @eid = eid ,@dept = dept ,@salary  = salary FROM inserted;

    INSERT INTO  dept_history (eid,olddept,newdept,uptime) values(@eid,null,@dept,GETDATE());

    INSERT INTO  sal_history (eid,oldsal,newsal,uptime) values(@eid,0,@salary,GETDATE());

END