触发器有两个特殊的表:插入表(instered表)和删除表(deleted表)
来源:互联网 发布:大华pss监控软件 编辑:程序博客网 时间:2024/06/10 06:38
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。
对表的操作
Inserted逻辑表
Deleted逻辑表
增加记录(insert)
存放增加的记录
无
删除记录(delete)
无
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。
Ø 创建触发器
语法
create trigger tgr_nameon table_namewith encrypion –加密触发器 for update...as Transact-SQL
# 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_insertgocreate trigger tgr_classes_inserton 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_deletegocreate trigger tgr_classes_deleteon 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_updategocreate trigger tgr_classes_updateon classes for updateas 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_columngocreate trigger tgr_classes_update_columnon classes for updateas --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; endgo--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;
更新列级触发器可以用update是否判断更新列记录;
# 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。
创建语法
create trigger tgr_nameon table_namewith encryption instead of update...as T-SQL
# 创建instead of触发器
if (object_id('tgr_classes_inteadOf', 'TR') is not null) drop trigger tgr_classes_inteadOfgocreate trigger tgr_classes_inteadOfon 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--testselect * 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_messagegocreate trigger tgr_messageon student after insert, updateas raisError('tgr_message触发器被触发', 16, 10);go--testinsert 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_messageon studentafter deleteas raisError('tgr_message触发器被触发', 16, 10);go--testdelete 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 ton t.object_id = te.object_idwhere 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_datagocreate trigger tgr_valid_dataon studentafter insertas 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; endgo--testinsert 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 loggocreate table log( id int identity(1, 1) primary key, action varchar(20), createDate datetime default getDate())goif (exists (select * from sys.objects where name = 'tgr_student_log')) drop trigger tgr_student_loggocreate trigger tgr_student_logon studentafter insert, update, deleteas 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'); endgo--testinsert 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;
出处:
blog:http://blog.csdn.net/IBM_hoojo
本文版权归作者和博客园共有,欢迎转载,但未经作者同意必须保留此段声明,且在文章页面明显位置给出原文连接,否则保留追究法律责任的权利。
版权所有,转载请注明出处 本文出自:
版权所有,欢迎转载,转载请注明出处,谢谢
»下一篇:SQL Server 数据库安全
- 触发器有两个特殊的表:插入表(instered表)和删除表(deleted表)
- 触发器deleted 表和 inserted 表详解!!!
- 触发器deleted 表和 inserted 表详解
- 触发器deleted 表和 inserted 表详解!!!
- 触发器中的 inserted表和deleted
- 触发器中虚拟表 inserted 和 deleted
- 触发器中的 inserted表和deleted
- 触发器中的inserted和deleted表
- SQL SERVER 触发器 inserted和deleted表
- 触发器中两个特殊表的应用
- 触发器中的inserted表和deleted表介绍
- SQL触发器中的deleted表和inserted表
- SQL触发器中的deleted表和inserted表
- sql触发器deleted 表和 inserted 表简介
- SQL触发器中的inserted表和deleted表
- 特殊的线性表-----栈---栈的插入和删除
- SQLServer触发器相关的inserted表与deleted表
- 相同表结构 一个表结构插入更新删除更新同步另外一个表 触发器设计 inserted,deleted 均为系统临时表
- mysql存储过程详解
- windows下模拟linux软件
- -webkit-animation的使用方法
- HDU 1495 非常可乐
- 虚拟化三剑客专题-VMware(下)
- 触发器有两个特殊的表:插入表(instered表)和删除表(deleted表)
- 为OLED屏增加GUI支持2:2D图形库
- 对onreadystatechange属性的理解
- 计算机学院大学生程序设计竞赛(2015’12)Polygon
- 虚拟化三剑客专题-VMware(上)
- C++中string、int常见类型转换(含代码演示)
- 移动互联网长连接方案实例
- install devstack (liberty) in ubuntu14.04(完整解决)
- Objective C运行时(runtime)技术的几个要点总结