创建insert类型触发器

--创建insert插入类型触发器
if (object_id('tgr_classes_insert','tr') is not null)
drop trigger tgr_classes_insert
go
create trigger tgr_classes_insert
on classes
for insert --插入触发
as
--定义变量
declare @id int,@name varchar(20),@temp int;
--在inserted表中查询已经插入记录信息
select @id = id,@name = name from inserted;
set @name = @name + convert(varchar,@id);
set @temp = @id / 2;
insert into student values(@name,18 + @id,@temp,@id);
print '添加学生成功！';
go
--插入数据
insert into classes values('5班',getDate());
--查询数据
select from classes;
select from student order by id;
insert触发器，会在inserted表中添加一条刚插入的记录。

创建delete类型触发器

--delete删除类型触发器
if (object_id('tgr_classes_delete','TR') is not null)
drop trigger tgr_classes_delete
go
create trigger tgr_classes_delete
on classes
for delete --删除触发
as
print '备份数据中……';
if (object_id('classesBackup','U') is not null)
--存在classesBackup，直接插入数据
insert into classesBackup select name,createDate from deleted;
else
--不存在classesBackup创建再插入
select * into classesBackup from deleted;
print '备份数据成功！';
go

--不显示影响行数
--set nocount on;
delete classes where name = '5班';
--查询数据
select from classes;
select from classesBackup;
delete触发器会在删除数据的时候，将刚才删除的数据保存在deleted表中。

创建update类型触发器

--update更新类型触发器
if (object_id('tgr_classes_update','TR') is not null)
drop trigger tgr_classes_update
go
create trigger tgr_classes_update
on classes
for update
as
declare @oldName varchar(20),@newName varchar(20);
--更新前的数据
select @oldName = name from deleted;
if (exists (select from student where name like '%'+ @oldName + '%'))
begin
--更新后的数据
select @newName = name from inserted;
update student set name = replace(name,@oldName,@newName) where name like '%'+ @oldName + '%';
print '级联修改数据成功！';
end
else
print '无需修改student表！';
go
--查询数据
select from student order by id;
select * from classes;
update classes set name = '五班' where name = '5班';
update触发器会在更新数据后，将更新前的数据保存在deleted表中，更新后的数据保存在inserted表中。

update更新列级触发器

if (object_id('tgr_classes_update_column','TR') is not null)
drop trigger tgr_classes_update_column
go
create trigger tgr_classes_update_column
on classes
for update
as
--列级触发器：是否更新了班级创建时间
if (update(createDate))
begin
raisError('系统提示：班级创建时间不能修改！',16,11);
rollback tran;
end
go
--测试
select from student order by id;
select from classes;
update classes set createDate = getDate() where id = 3;
update classes set name = '四班' where id = 7;

创建instead of触发器

if (object_id('tgr_classes_inteadOf','TR') is not null)
drop trigger tgr_classes_inteadOf
go
create trigger tgr_classes_inteadOf
on classes
instead of delete/,update,insert/
as
declare @id int,@name varchar(20);
--查询被删除的信息，病赋值
select @id = id,@name = name from deleted;
print 'id: ' + convert(varchar,@id) + ',name: ' + @name;
--先删除student的信息
delete student where cid = @id;
--再删除classes的信息
delete classes where id = @id;
print '删除[ id: ' + convert(varchar,name: ' + @name + ' ] 的信息成功！';
go
--test
select from student order by id;
select from classes;
delete classes where id = 7;

显示自定义消息raiserror

if (object_id('tgr_message','TR') is not null)
drop trigger tgr_message
go
create trigger tgr_message
on student
after insert,update
as raisError('tgr_message触发器被触发',10);
go
--test
insert into student values('lily',22,1,7);
update student set sex = 0 where name = 'lucy';
select * from student order by id;

修改触发器

alter trigger tgr_message
on student
after delete
as raisError('tgr_message触发器被触发',10);
go
--test
delete from student where name = 'lucy';

启用、禁用触发器

--禁用触发器
disable trigger tgr_message on student;
--启用触发器
enable trigger tgr_message on student;

查询创建的触发器信息

--查询已存在的触发器
select from sys.triggers;
select from sys.objects where type = 'TR';

--查看触发器触发事件
select te.* from sys.trigger_events te join sys.triggers t
on t.object_id = te.object_id
where t.parent_class = 0 and t.name = 'tgr_valid_data';

--查看创建触发器语句
exec sp_helptext 'tgr_message';

示例，验证插入数据

if ((object_id('tgr_valid_data','TR') is not null))
drop trigger tgr_valid_data
go
create trigger tgr_valid_data
on student
after insert
as
declare @age int,@name varchar(20);
select @name = s.name,@age = s.age from inserted s;
if (@age < 18)
begin
raisError('插入新数据的age有问题',1);
rollback tran;
end
go
--test
insert into student values('forest',2,7);
insert into student values('forest',7);
select * from student order by id;

示例，操作日志

if (object_id('log','U') is not null)
drop table log
go
create table log(
id int identity(1,1) primary key,action varchar(20),createDate datetime default getDate()
)
go
if (exists (select from sys.objects where name = 'tgr_student_log'))
drop trigger tgr_student_log
go
create trigger tgr_student_log
on student
after insert,delete
as
if ((exists (select 1 from inserted)) and (exists (select 1 from deleted)))
begin
insert into log(action) values('updated');
end
else if (exists (select 1 from inserted) and not exists (select 1 from deleted))
begin
insert into log(action) values('inserted');
end
else if (not exists (select 1 from inserted) and exists (select 1 from deleted))
begin
insert into log(action) values('deleted');
end
go
--test
insert into student values('king',7);
update student set sex = 0 where name = 'king';
delete student where name = 'king';
select from log;
select * from student order by id;