SQL查詢語句 group by后， 字符串合並

合並列值 
--*******************************************************************************************
表結構，數據如下： 
id    value 
----- ------ 
   aa 
   bb 
   aaa 
   bbb 
   ccc 

需要得到結果： 
id    values 
------ ----------- 
     aa,bb 
     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      
----------- ----------- 
         aa,bb 
         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 [values]= STUFF(REPLACE(REPLACE( 
            ( 
                SELECT value FROM tb N 
                WHERE id = A.id 
                FOR XML AUTO 
            ), ' <N value="', ','), '"/>', ''), 1, 1, '') 
)N 
drop table tb 

/* 
id          values 
----------- ----------- 
         aa,bb 
         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 
----------- -------------------- 
         aa,bb 
         aaa,bbb,ccc 

(2 row(s) affected) 

*/

demo:

select
  BeginCity,EndCity,FanDian,
     [CangWei]=stuff((select '/'+[CangWei] from test1 t  
     where t.BeginCity=Test1.BeginCity  and t.EndCity=Test1.EndCity  and t.FanDian=Test1.FanDian   
     for xml path('')), 1, 1, '') 
from  
Test1 
group by 
BeginCity,EndCity,FanDian

參考:  http://bbs.csdn.net/topics/330188225

          http://bbs.csdn.net/topics/330182340

 

https://www.cnblogs.com/qixuejia/p/4241932.html