SQLSERVER利用FOR XML PATH实现分组拼接字符串

首先看一下数据结构表

 1 IF(OBJECT_ID(\'tempdb..#tProduct\')IS NOT NULL)
 2     DROP TABLE #tProduct
 3 SELECT * INTO #tProduct FROM(
 4     SELECT 1 AS CatagoryID,1 AS ProductID,\'aaa\'AS ProductName
 5     UNION 
 6     SELECT 1 AS CatagoryID,2 AS ProductID,\'bbb\'AS ProductName
 7     UNION 
 8     SELECT 1 AS CatagoryID,3 AS ProductID,\'ccc\'AS ProductName
 9     UNION 
10     SELECT 2 AS CatagoryID,4 AS ProductID,\'xxx\'AS ProductName
11     UNION 
12     SELECT 2 AS CatagoryID,5 AS ProductID,\'yyy\'AS ProductName
13     UNION 
14     SELECT 2 AS CatagoryID,6 AS ProductID,\'zzz\'AS ProductName
15 )TEMP
16 --SELECT * FROM #tProduct

 

所需的查询结果

CatagoryID	Products
1	aaa,bbb,ccc
2	xxx,yyy,zzz

 

 

 

 

 

查询语句实现

1 SELECT DISTINCT T1.CatagoryID
2 ,Products=REPLACE((SELECT ProductNameAS [data()] FROM #tProduct T2 WHERE T2.CatagoryID=T1.CatagoryID ORDER BY ProductID FOR XML PATH(\'\')),\' \',\',\')
3 FROM #tProduct T1 ORDER BY CatagoryID

 

讲解：请依次执行以下语句查看结果

更多关于FOR XML PATH 请参考msdn。

1、使用FOR XML PATH生成XML文档字符串

1 SELECT CatagoryID,ProductID,ProductName FROM #tProduct
2 FOR XML PATH(\'Products\'),ROOT(\'root\')

 

简化一下

1 SELECT ProductName FROM #tProduct
2 FOR XML PATH(\'\')

 

2、使用data()去掉XML标签元素(这样就使得一列的值构成一个以空格为分隔符的字符串)

1 SELECT ProductName AS [data()] FROM #tProduct
2 FOR XML PATH(\'\')

 

说明：通过使用 data() 作为列名， SELECT 语句将返回 ProductName 的列表。又由于FOR XML PATH(‘’) 指定了一个空字符串作为行元素名，因此不会生成元素

3、见最终的实现语句