SQL Server 触发器

create trigger tgr_name
on table_name
with encrypion –加密触发器
for update...
as

Transact-SQL

--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;

--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;

--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';

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;

create trigger tgr_name
on table_name
with encryption

instead of update...
as

T-SQL

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, @id) + ', name: ' + @name + ' ] 的信息成功！';
go

--test
select * from student order by id;
select * from classes;
delete classes where id = 7;

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', 16, 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;

alter trigger tgr_message
on student
after delete
as raisError('tgr_message触发器被触发', 16, 10);
go

--test
delete from student where name = 'lucy';

--禁用触发器

disable trigger tgr_message on student;

--启用触发器

enable trigger tgr_message on student;

--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';

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', 16, 1);
rollback tran;
end
go

--test

insert into student values('forest', 2, 0, 7);

insert into student values('forest', 22, 0, 7);
select * from student order by id;

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, update, 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', 22, 1, 7);
update student set sex = 0 where name = 'king';
delete student where name = 'king';
select * from log;
select * from student order by id;