SQL SERVER 觸發(fā)器介紹

create trigger tgr_name
on table_name
with encrypion –加密觸發(fā)器
for update...
as
Transact-SQL 

# 創(chuàng)建insert類型觸發(fā)器

--創(chuàng)建insert插入類型觸發(fā)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 --插入觸發(fā)
as
--定義變量
declare @id int, @name varchar(20), @temp int;
--在inserted表中查詢已經(jīng)插入記錄信息
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 '添加學(xué)生成功！';
go
--插入數(shù)據(jù)
insert into classes values('5班', getDate());
--查詢數(shù)據(jù)
select * from classes;
select * from student order by id; 
insert觸發(fā)器，會在inserted表中添加一條剛插入的記錄。


# 創(chuàng)建delete類型觸發(fā)器

--delete刪除類型觸發(fā)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 --刪除觸發(fā)
as
print '備份數(shù)據(jù)中……'; 
if (object_id('classesBackup', 'U') is not null)
--存在classesBackup，直接插入數(shù)據(jù)
insert into classesBackup select name, createDate from deleted;
else
--不存在classesBackup創(chuàng)建再插入
select * into classesBackup from deleted;
print '備份數(shù)據(jù)成功！';
go
--
--不顯示影響行數(shù)
--set nocount on;
delete classes where name = '5班';
--查詢數(shù)據(jù)
select * from classes;
select * from classesBackup; 
delete觸發(fā)器會在刪除數(shù)據(jù)的時候，將剛才刪除的數(shù)據(jù)保存在deleted表中。


# 創(chuàng)建update類型觸發(fā)器

--update更新類型觸發(fā)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);
--更新前的數(shù)據(jù)
select @oldName = name from deleted;
if (exists (select * from student where name like '%'+ @oldName + '%'))
begin
--更新后的數(shù)據(jù)
select @newName = name from inserted;
update student set name = replace(name, @oldName, @newName) where name like '%'+ @oldName + '%';
print '級聯(lián)修改數(shù)據(jù)成功！';
end
else
print '無需修改student表！';
go
--查詢數(shù)據(jù)
select * from student order by id;
select * from classes;
update classes set name = '五班' where name = '5班'; 
update觸發(fā)器會在更新數(shù)據(jù)后，將更新前的數(shù)據(jù)保存在deleted表中，更新后的數(shù)據(jù)保存在inserted表中。


# update更新列級觸發(fā)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
--列級觸發(fā)器：是否更新了班級創(chuàng)建時間
if (update(createDate))
begin
raisError('系統(tǒng)提示：班級創(chuàng)建時間不能修改！', 16, 11);
rollback tran;
end
go
--測試
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 

# 創(chuàng)建instead of觸發(fā)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);
--查詢被刪除的信息，病賦值
select @id = id, @name = name from deleted;
print 'id: ' + convert(varchar, @id) + ', name: ' + @name;
--先刪除student的信息
delete student where cid = @id;
--再刪除classes的信息
delete classes where id = @id;
print '刪除[ 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; 

# 顯示自定義消息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觸發(fā)器被觸發(fā)', 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; 

# 修改觸發(fā)器

alter trigger tgr_message
on student
after delete
as raisError('tgr_message觸發(fā)器被觸發(fā)', 16, 10);
go
--test
delete from student where name = 'lucy'; 

# 啟用、禁用觸發(fā)器

--禁用觸發(fā)器
disable trigger tgr_message on student;
--啟用觸發(fā)器
enable trigger tgr_message on student; 

# 查詢創(chuàng)建的觸發(fā)器信息

--查詢已存在的觸發(fā)器
select * from sys.triggers;
select * from sys.objects where type = 'TR';

--查看觸發(fā)器觸發(fā)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';

--查看創(chuàng)建觸發(fā)器語句
exec sp_helptext 'tgr_message'; 


# 示例，驗(yàn)證插入數(shù)據(jù)

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('插入新數(shù)據(jù)的age有問題', 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; 

# 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, 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;