一.定义表变量

代码如下:

DECLARE @T1 table

(

UserID int ,

UserName nvarchar(50),

CityName nvarchar(50)

);

insert into @T1 (UserID,UserName,CityName) values (1,'a','上海')

insert into @T1 (UserID,UserName,CityName) values (2,'b','北京')

insert into @T1 (UserID,UserName,CityName) values (3,'c','上海')

insert into @T1 (UserID,UserName,CityName) values (4,'d','北京')

insert into @T1 (UserID,UserName,CityName) values (5,'e','上海')

select * from @T1

-----最优的方式

SELECT CityName,STUFF((SELECT ',' + UserName FROM @T1 subTitle WHERE CityName=A.CityName FOR XML PATH('')),1, 1, '') AS A

FROM @T1 A

GROUP BY CityName

----第二种方式

SELECT B.CityName,LEFT(UserList,LEN(UserList)-1)

FROM (

SELECT CityName,(SELECT UserName+',' FROM @T1 WHERE CityName=A.CityName FOR XML PATH('')) AS UserList

FROM @T1 A

GROUP BY CityName

) B

stuff(select ',' + fieldname from tablename for xml path('')),1,1,'')

这一整句的作用是将多行fieldname字段的内容串联起来，用逗号分隔。

for xml path是SQL Server 2005以后版本支持的一种生成XML的方式。

stuff函数的作用是去掉字符串最前面的逗号分隔符。

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