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

使用XML路径不会完美地连接你可能期望…它会将“&”替换为“&”，也会混淆<”和“>” .．.也许还有其他一些事情，不确定……但是你可以试试这个

我想到了一个变通办法…您需要替换:

FOR XML PATH('')
)

:

FOR XML PATH(''),TYPE
).value('(./text())[1]','VARCHAR(MAX)')

.．.或者NVARCHAR(MAX)如果这是你使用的。

为什么SQL没有一个串联聚合函数?这是PITA。

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

没有看到任何交叉应用的答案，也不需要XML提取。这是凯文·费尔柴尔德的一个略有不同的版本。在更复杂的查询中使用它更快更容易:

   select T.ID
,MAX(X.cl) NameValues
 from #YourTable T
 CROSS APPLY 
 (select STUFF((
    SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX))
    FROM #YourTable 
    WHERE (ID = T.ID) 
    FOR XML PATH(''))
  ,1,2,'')  [cl]) X
  GROUP BY T.ID

如果是SQL Server 2017或SQL Server Vnext, SQL Azure，您可以使用STRING_AGG如下所示:

SELECT id, STRING_AGG(CONCAT(name, ':', [value]), ', ')
FROM #YourTable 
GROUP BY id

使用Stuff和for xml路径操作符将行连接到字符串:Group By两列——>

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 (1,'B',5)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)

-- retrieve each unique id and name columns and concatonate the values into one column
SELECT 
  [ID], 
  STUFF((
    SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) -- CONCATONATES EACH APPLICATION : VALUE SET      
    FROM #YourTable 
    WHERE (ID = Results.ID and Name = results.[name] ) 
    FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
  ,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID


SELECT 
  [ID],[Name] , --these are acting as the group by clause
  STUFF((
    SELECT ', '+  CAST([Value] AS VARCHAR(MAX)) -- CONCATONATES THE VALUES FOR EACH ID NAME COMBINATION 
    FROM #YourTable 
    WHERE (ID = Results.ID and Name = results.[name] ) 
    FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
  ,1,2,'') AS  NameValues
FROM #YourTable Results
GROUP BY ID, name

DROP TABLE #YourTable