1 --1.) 创建测试用的表(testTable)
  2 if exists (select * from sysobjects where name='testTable')
  3 drop table testTable
  4 GO
  5 Create Table testTable
  6 (
  7 testField varchar(50)
  8 )
  9
 10  select * from testTable
 11
 12
 13
 14 --2.) 创建基于表(testTable)的触发器(testTrigger)
 15 IF EXISTS (Select name FROM sysobjects Where name = 'testTrigger' AND type = 'TR')
 16 Drop TRIGGER testTrigger
 17 GO
 18 Create Trigger testTrigger
 19 ON testTable
 20 for Insert,Delete,Update
 21 AS
 22 if exists(select * from inserted)
 23      if exists(select * from deleted)
 24          print '...更新'
 25      else
 26          print '...插入'
 27 else
 28      if exists(select * from deleted)
 29          print '...删除'
 30 Go
 31
 32
 33 --.) 操作testTable表,测试触发器testTrigger
 34 --分别执行Insert Into语句,Update语句,Delete语句,看看效果
 35 Insert Into testTable values ('testContent!')
 36
 37 Update testTable Set testField = 'UpdateContent'
 38
 39 Delete From testTable
 40
 41 select * from testTable
 42
 43
 44 --用到的功能有:
 45         --1.如果我更改了学生的学号,我希望他的借书记录仍然与这个学生相关(也就是同时更改借书记录表的学号);
 46         --2.如果该学生已经毕业，我希望删除他的学号的同时，也删除它的借书记录，等等。
 47
 48  --这时候可以用到触发器。对于需求1，创建一个Update触发器：
 49
 50      Create Trigger truStudent
 51
 52        On student      --在Student表中创建触发器
 53        instead of Update      --为什么事件触发
 54      As           --事件触发后所要做的事情
 55        if Update(stuID)
 56        begin
 57
 58          Update borrow
 59            Set stuID=i.stuID
 60            From borrow as br , Deleted as d ,Inserted as i      --Deleted和Inserted临时表
 61            Where br.stuID=d.stuID
 62
 63        end
 64
 65 drop trigger truStudent
 66 UPDATE student set stuID='1006' WHERE stuID='1005'
 67
 68
 69     Create trigger trdStudent
 70        On Student
 71        instead of Delete
 72      As
 73      Delete Borrow
 74 　　　From Borrow as br , Deleted as d Where br.StuID=d.stuID
 75
 76 drop trigger trdStudent
 77 delete FROM student WHERE stuID='1004'
 78
 79 disable trigger trdStudent on Student
 80
 81 select * from book
 82 select * from borrow
 83 select * from student
 84
 85
 86 --创建触发器（对删除表的约束）
 87 create trigger droptabel
 88 on database
 89 for drop_table
 90 as
 91 print'删除表吗？'
 92 print'不能删除表'
 93 rollback transaction
 94 go
 95
 96 drop table students
 97 disable trigger droptabel on database　　　　--关闭触发器
 98 enable trigger droptabel on database
 99
100
101
102
103
104 CREATE TABLE students  --学生信息表
105 (
106   stuID CHAR(10) primary key,  --学生编号
107   stuName  CHAR(10) NOT NULL ,     --学生名称
108   major  CHAR(50) NOT NULL    --专业
109 )
110 GO
111
112
113 CREATE TABLE borrowS  --借书表
114 (
115  borrowID  CHAR(10) primary key,    --借书编号
116 stuID CHAR(10) NOT NULL, --学生编号
117 BID  CHAR(10) NOT NULL,--图书编号
118  T_time  datetime NOT NULL,   --借出日期
119  B_time  datetime    --归还日期
120 )
121 GO
122
123 SElect * from students
124 select * from borrows
125
126 Create Trigger truStudents
127
128        On students      --在Student表中创建触发器
129        for Update      --为什么事件触发
130      As           --事件触发后所要做的事情
131        if Update(stuID)
132        begin
133
134          Update borrows
135            Set stuID=i.stuID
136            From borrows as br , Deleted as d ,Inserted as i      --Deleted和Inserted临时表
137            Where br.stuID=d.stuID
138
139        end
140
141
142
143 UPDATE studentS set stuID='1006' WHERE stuID='1005'
144
145
146     Create trigger trStudent
147        On Students
148        for Delete
149      As
150        Delete borrows
151          From borrows AS br , Deleted AS d
152          Where br.stuID=d.stuID
153
154
155 drop trigger trStudent
156
157
158 delete from students where stuID='1001'