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

------解决方案--------------------

执行这样的查询语句:
SQL code
select xh=row_number()over(order by id),* from pl