合並列值
--*******************************************************************************************
表結構，數據如下：
id value
----- ------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
需要得到結果：
id values
------ -----------
1 aa,bb
2 aaa,bbb,ccc
即：group by id, 求 value 的和（字符串相加）
1. 舊的解決方法(在sql server 2000中只能用函數解決。)
--=============================================================================
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
Go
--1. 創建處理函數
CREATE FUNCTION dbo.f_strUnite(@id int)
RETURNS varchar(8000)
AS
BEGIN
DECLARE @str varchar(8000)
SET @str = ''
SELECT @str = @str + ',' + value FROM tb WHERE id=@id
RETURN STUFF(@str, 1, 1, '')
END
GO
-- 調用函數
SELECt id, value = dbo.f_strUnite(id) FROM tb GROUP BY id
drop table tb
drop function dbo.f_strUnite
go
/*
id value
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
（所影響的行數為 2 行）
*/
--===================================================================================
2. 新的解決方法(在sql server 2005中用OUTER APPLY等解決。)
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
-- 查詢處理
SELECT * FROM(SELECT DISTINCT id FROM tb ) A OUTER APPLY (
SELECT value= STUFF(
REPLACE((
SELECT value FROM tb N
WHERE N.id = A.id
FOR XML AUTO
),' ',''), 1, 1, '') ) AS P
drop table tb
/*
id values
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
(2 行受影響)
*/
--SQL2005中的方法2
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
select id, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '')
from tb
group by id
/*
id values
----------- --------------------
1 aa,bb
2 aaa,bbb,ccc
(2 row(s) affected)
*/
drop table tb