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Server触发器和事务用法示例

2020年1月31日 - 首页

本文实例讲述了SQL
Server触发器和事务用法。分享给大家供大家参考,具体如下:

SQL Server 通过触发器用来保证业务逻辑和数据的完整性。在SQL
Server中,触发器是一种特殊类型的存储过程,可在执行语言事件时自动触发。SQL
Server中触发器包括三种:DML触发器、DDL触发器和登录触发器。

新增和删除触发器

alter trigger tri_TC on t_c for INSERT,deleteasbegin set XACT_ABORT ON declare @INSERTCOUNT int; declare @DELETECOUNT int; declare @UPDATECOUNT int; set @INSERTCOUNT = (select COUNT(*) from inserted); set @DELETECOUNT = (select COUNT(*) from deleted); set @UPDATECOUNT = () if(@INSERTCOUNT  0) begin insert into t_c2 select * from inserted; end else if(@DELETECOUNT  0) begin delete t_c2 where exists(select temp.cid from deleted temp where temp.cid=t_c2.cid); endend

SQL
Server将触发器和触发它的语句放在一个可回滚事务中,如果触发器发生异常,则与该触发器相关的语句自动回滚。

更新触发器和事务

DML的功能(优点):

事务主要用在数据的保护,在多表更新时,事务保存所有事务下的更新语句就不会提交,数据也就不能更新成功

alter trigger tri_TC_Update on t_c for updateasbegin declare @delcount int; set @delcount = (select count(*) from deleted); if(@delcount  0) begin begin transaction triUpdate --定义事务 declare @cname varchar(100); select @cname = cname from inserted; --保存更新后的内容 update t_c2 set cname = @cname where cid = (select cid from deleted); --更新 if (@@error  0) begin rollback transaction triUpdate; --事务回滚 end else begin commit transaction triUpdate; --事务提交 end endend

注意:有日志操作的行为才会激活触发器。例如truncate
table删除表中所有数据,并没有执行日志操作,所以不会激活delete触发器。

存储过程

澳门太阳集团,创建触发器

DML触发器分为:

其中after触发器要求只有执行某一操作insert、update、delete之后触发器才被触发,且只能定义在表上。而instead
of触发器表示并不执行其定义的操作(insert、update、delete)而仅是执行触发器本身。既可以在表上定义instead
of触发器,也可以在视图上定义。

触发器有两个特殊的表:插入表(instered表)和删除表(deleted表)。这两张是逻辑表也是虚表。有系统在内存中创建者两张表,不会存储在数据库中。而且两张表的都是只读的,只能读取数据而不能修改数据。这两张表的结果总是与被改触发器应用的表的结构相同。当触发器完成工作后,这两张表就会被删除。Inserted表的数据是插入或是修改后的数据,而deleted表的数据是更新前的或是删除的数据。

  Inserted逻辑表 Deleted逻辑表
增加记录(insert) 存放增加的记录
删除记录(delete) 存放被删除的记录
修改记录(update) 存放更新后的记录 存放更新前的记录

Update数据的时候就是先删除表记录,然后增加一条记录。这样在inserted和deleted表就都有update后的数据记录了。注意的是:触发器本身就是一个事务,所以在触发器里面可以对修改数据进行一些特殊的检查。如果不满足可以利用事务回滚,撤销操作。

if(exists(select name from sysobjects s where s.name='pro_fun' and s.type='p')) drop procedure pro_fungo create procedure pro_funas select * from tablegoexec pro_fun

创建触发器的语法:

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

 

游标

创建insert类型触发器

insert触发器,会在inserted表中添加一条刚插入的记录。

--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;

 

declare @qybh varchar(10)declare cur cursor for select distinct qybh from PJ_EnterpriseInputopen curfetch next from cur into @qybhwhile @@fetch_status = 0 begin print(@qybh) fetch next from cur into @qybh endclose curdeallocate cur

创建delete类型触发器

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。

--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;

 

视图

创建update类型触发器

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';

 

alter view CreateViewas select qybh from CreateViewgo

update更新列级触发器

更新列级触发器可以用update是否判断更新列记录;

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;

定义方法

instead of 类型触发器

instead of
触发器表示并不执行其定义的操作(insert、update、delete)而仅是执行触发器本身的内容。

语法:

create trigger tgr_name
on table_name
with encryption
    instead of update...
as
    T-SQL
alter function funName(@str1 varchar(10),@str2 varchar(10))returns varchar(10)asbegin declare @returnStr varchar(10) set @returnStr = 'false' if(@str1  @str2) set @returnStr = 'true' return @returnStrendselect dbo.funName(... , ...)

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, @id) + ', name: ' + @name + ' ] 的信息成功!';
go
--test
select * from student order by id;
select * from classes;
delete classes where id = 7;

定义表变量

显示错误信息(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', 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;
declare @qybhTable table (id varchar(32),qybh varchar(30))insert into @qybhTableselect id,qybh from PJ_EnterpriseInputselect * from @qybhTable

修改触发器

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';

 

case when then 条件统计时的使用

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;

 

selectsum(case when z.watchName='注册监理工程师' then 1 else 0 end),sum(case when z.watchName='xinza' then 1 else 0 end),sum(case when z.watchName='监理员' then 1 else 0 end)from zu_corjl zright join zu_corjltemp t on t.corID=z.corID

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';

 

希望本文所述对大家SQL Server数据库程序设计有所帮助。

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', 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;

本文代码来源:

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