MSSQL編號重排常見解決方案
--> Title : MSSQL編號重排常見解決方案
--> Author : wufeng4552
--> Date : 2009-11-25
if object_id('[tb]') is not null drop table [tb]
go
create table [tb] (ID int,ID1 nvarchar(6),ID2 sql_variant)
insert into [tb]
select 1,'001',null union all
select 2,'001',null union all
select 3,'001',null union all
select 4,'002',null union all
select 5,'002',null union all
select 6,'002',null
--方法1 Update
declare @id1 varchar(3),@id2 int
update [tb] set @id2=case when @id1=id1 then @id2+1 else 1 end,
id2=@id2,@id1=id1
select * from tb
-->查詢結果
/*
ID ID1 ID2
----------- ------ -----
1 001 1
2 001 2
3 001 3
4 002 1
5 002 2
6 002 3
(6 個資料列受到影響)
*/
--方法2 子查詢
update t set
id2=(select count(*) from [tb] where id1=t.id1 and id<=t.id)
from [tb] t
select * from [tb]
-->查詢結果
/*
ID ID1 ID2
----------- ------ -----
1 001 1
2 001 2
3 001 3
4 002 1
5 002 2
6 002 3
(6 個資料列受到影響)
*/
--方法3 臨時表
if object_id('tempdb..#')is not null drop table #
select *,cnt=identity(int,0,1)into # from tb order by id1,id
update a set id2=b.cnt-c.cnt+1
from [tb] a ,# b,
(select id1,min(cnt)cnt from # group by id1)c
where a.id1=b.id1 and a.id=b.id and b.id1=c.id1
select * from tb
-->查詢結果
/*
ID ID1 ID2
----------- ------ -----
1 001 1
2 001 2
3 001 3
4 002 1
5 002 2
6 002 3
(6 個資料列受到影響)
*/
--方法MSSQL2005 cte
;with cte
as
(select *,cnt=row_number()over(partition by ID1 order by (select 1)) from [tb])
update cte set id2=cnt
select * from tb
-->查詢結果
/*
ID ID1 ID2
----------- ------ -----
1 001 1
2 001 2
3 001 3
4 002 1
5 002 2
6 002 3
(6 個資料列受到影響)
*/