如果group by只包含一个项目，您可以通过以下方式显著提高性能:

SELECT 
  [ID],

CASE WHEN MAX( [Name]) = MIN( [Name]) THEN 
MAX( [Name]) NameValues
ELSE

  STUFF((
    SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) 
    FROM #YourTable 
    WHERE (ID = Results.ID) 
    FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
  ,1,2,'') AS NameValues

END

FROM #YourTable Results
GROUP BY ID

另一个不带垃圾的例子:"，TYPE).value('(./text())[1]'，'VARCHAR(MAX)')"

WITH t AS (
    SELECT 1 n, 1 g, 1 v
    UNION ALL 
    SELECT 2 n, 1 g, 2 v
    UNION ALL 
    SELECT 3 n, 2 g, 3 v
)
SELECT g
        , STUFF (
                (
                    SELECT ', ' + CAST(v AS VARCHAR(MAX))
                    FROM t sub_t
                    WHERE sub_t.g = main_t.g
                    FOR XML PATH('')
                )
                , 1, 2, ''
        ) cg
FROM t main_t
GROUP BY g

输入-输出是

*************************   ->  *********************
*   n   *   g   *   v   *       *   g   *   cg      *
*   -   *   -   *   -   *       *   -   *   -       *
*   1   *   1   *   1   *       *   1   *   1, 2    *
*   2   *   1   *   2   *       *   2   *   3       *
*   3   *   2   *   3   *       *********************
*************************   

SQL Server 2005及其后续版本允许您创建自己的自定义聚合函数，包括像连接这样的功能—请参阅链接文章底部的示例。

使用Sql Server 2005及以上版本的另一种选择

---- test data
declare @t table (OUTPUTID int, SCHME varchar(10), DESCR varchar(10))
insert @t select 1125439       ,'CKT','Approved'
insert @t select 1125439       ,'RENO','Approved'
insert @t select 1134691       ,'CKT','Approved'
insert @t select 1134691       ,'RENO','Approved'
insert @t select 1134691       ,'pn','Approved'

---- actual query
;with cte(outputid,combined,rn)
as
(
  select outputid, SCHME + ' ('+DESCR+')', rn=ROW_NUMBER() over (PARTITION by outputid order by schme, descr)
  from @t
)
,cte2(outputid,finalstatus,rn)
as
(
select OUTPUTID, convert(varchar(max),combined), 1 from cte where rn=1
union all
select cte2.outputid, convert(varchar(max),cte2.finalstatus+', '+cte.combined), cte2.rn+1
from cte2
inner join cte on cte.OUTPUTID = cte2.outputid and cte.rn=cte2.rn+1
)
select outputid, MAX(finalstatus) from cte2 group by outputid

如果group by只包含一个项目，您可以通过以下方式显著提高性能:

SELECT 
  [ID],

CASE WHEN MAX( [Name]) = MIN( [Name]) THEN 
MAX( [Name]) NameValues
ELSE

  STUFF((
    SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) 
    FROM #YourTable 
    WHERE (ID = Results.ID) 
    FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
  ,1,2,'') AS NameValues

END

FROM #YourTable Results
GROUP BY ID

这只是Kevin Fairchild的文章的补充(顺便说一句，非常聪明)。我本来会把它作为一个评论，但我还没有足够的分数:)

我将这个想法用于我正在工作的视图，然而我正在连接的项目包含空间。因此，我稍微修改了代码，不再使用空格作为分隔符。

再次感谢你酷炫的解决办法，凯文!

CREATE TABLE #YourTable ( [ID] INT, [Name] CHAR(1), [Value] INT ) 

INSERT INTO #YourTable ([ID], [Name], [Value]) VALUES (1, 'A', 4) 
INSERT INTO #YourTable ([ID], [Name], [Value]) VALUES (1, 'B', 8) 
INSERT INTO #YourTable ([ID], [Name], [Value]) VALUES (2, 'C', 9) 

SELECT [ID], 
       REPLACE(REPLACE(REPLACE(
                          (SELECT [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) as A 
                           FROM   #YourTable 
                           WHERE  ( ID = Results.ID ) 
                           FOR XML PATH (''))
                        , '</A><A>', ', ')
                ,'<A>','')
        ,'</A>','') AS NameValues 
FROM   #YourTable Results 
GROUP  BY ID 

DROP TABLE #YourTable