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利用触发器实现标识列连续。(支持批量插入)
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[ttt]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[ttt]
GO
/****** Object: Table [dbo].[ttt] Script Date: 2008-12-15 17:11:26 ******/
CREATE TABLE [dbo].[ttt] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[name] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,
[time] [datetime] NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[ttt] ADD
CONSTRAINT [PK_ttt] PRIMARY KEY CLUSTERED
(
[id]
) ON [PRIMARY]
GO
insert into ttt(name,time) values('logan',getdate());
insert into ttt(name,time) values('peter',getdate());
insert into ttt(name,time) values('man',getdate());
insert into ttt(name,time) values('lida',getdate());
insert into ttt(name,time) values('fcuandy',getdate());
select * from ttt
/*
1 logan 2008-12-15 17:36:37.780
2 peter 2008-12-15 17:36:37.780
3 man 2008-12-15 17:36:37.780
4 lida 2008-12-15 17:36:37.780
5 fcuandy 2008-12-15 17:36:37.793
*/
GO
CREATE TRIGGER tr ON ttt
INSTEAD OF INSERT
AS
SET IDENTITY_INSERT ttt ON
DECLARE @n INT
SELECT @n=MAX(id) FROM ttt
;WITH fc AS
(
SELECT n=1
UNION ALL
SELECT nn=n+1 FROM fc WHERE n<@n
),fc1 AS
(
SELECT n FROM fc a
LEFT JOIN ttt b
ON a.n = b.id
WHERE b.id IS NULL
)
INSERT ttt(id,name,time) SELECT n,name,time
FROM
(SELECT ROW_NUMBER() OVER (ORDER BY GETDATE()) idx,n FROM fc1) a
INNER JOIN
(
SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted
) b
ON a.idx=b.idx
DECLARE @r INT
SELECT @r=@@ROWCOUNT
SET IDENTITY_INSERT ttt OFF
INSERT ttt(name,time) SELECT name,time FROM
(
SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted
) x
WHERE idx>@r
GO
DELETE FROM ttt WHERE name = 'peter' OR name='lida'
GO
INSERT ttt SELECT 'xxx',getdate()
INSERT ttt SELECT 'yyy',GETDATE()
GO
SELECT * FROM ttt
/*
1 logan 2008-12-15 17:37:20.967
2 xxx 2008-12-15 17:37:21.013
3 man 2008-12-15 17:37:20.967
4 yyy 2008-12-15 17:37:21.030
5 fcuandy 2008-12-15 17:37:20.967
*/
DELETE FROM ttt WHERE name ='xxx' OR name='yyy'
INSERT ttt SELECT 'roy_88',GETDATE() UNION ALL SELECT 'limpire',GETDATE() UNION ALL SELECT '熊',GETDATE()
SELECT * FROM ttt
/*
1 logan 2008-12-15 17:38:29.450
2 roy_88 2008-12-15 17:38:29.530
3 man 2008-12-15 17:38:29.467
4 limpire 2008-12-15 17:38:29.530
5 fcuandy 2008-12-15 17:38:29.467
6 熊 2008-12-15 17:38:29.530
*/
本文来自CSDN博客,转载请标明出处:http://blog.csdn.net/fcuandy/archive/2008/12/15/3522876.aspx
/*-------------------------
*问题描述:表中采用了自增列删除记录会出现断号的情况,但是又想让它删除后自动重新编号?
*采用函数+触发器的方法替代IDENTITY的功能,并且解决断号问题
------------------------------------*/
--创建实现自增列的函数
create function f_getID()
returns int
as
begin
return(select isnull(max(id),0)+1 from tb)
end
go
--创建表
create table tb(id int primary key default dbo.f_getID() ,name varchar(20))
go
--创建触发器,在删除表中的记录时,自动更新记录的id,解决断号的烦恼
create trigger t_s_duanhao on tb
AFTER delete
as
declare @mid int
select @mid=min(id)-1
from deleted
update tb
set id=@mid,@mid=@mid+1
where id>@mid+1
go
--插入记录测试(只能一条条记录插入)
insert into tb(name) values('1哥')
insert into tb(name) values('2哥')
insert into tb(name) values('3哥')
insert into tb(name) values('4哥')
insert into tb(name) values('5哥')
insert into tb(name) values('6哥')
insert into tb(name) values('7哥')
insert into tb(name) values('8哥')
--显示插入的结果
select * from tb
--删除部分记录
delete from tb where name in('1哥','4哥','7哥','8哥')
--显示删除后的结果
select * from tb
/*--测试结果
id name
----------- --------------------
1 2哥
2 3哥
3 5哥
4 6哥
--*/
--删除环境
drop table tb
drop function f_getID