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：

1. 如果学生所在的班级存在，则班级表学生数+1。

2. 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