T_SQL 将一列多行数据合并为一行

SQL Server在进行数据迁移和报表处理的时候会遇到将一列多行数据拼接为一个字符串的情况，为了处理这个问题，在网上找了一些相关的资料，提供两种方法，供遇到类似问题的朋友们参考，也借此加深自己的印象。

Table：SC

期望得到的结果：

IF OBJECT_ID(N’SC’) IS NOT NULL

      BEGIN

            DROP TABLE SC

      END

ELSE

      BEGIN

            CREATE TABLE SC

            (

                  Student NVARCHAR(50),

                  Course NVARCHAR(50)

            )

            INSERT INTO SC

            SELECT N’张三’,N’大学语文’ UNION ALL

            SELECT N’李四’,N’大学语文’ UNION ALL

            SELECT N’张三’,N’书法鉴赏’ UNION ALL

            SELECT N’张三’,N’音乐赏析’ UNION ALL

            SELECT N’李四’,N’电影赏析’           

      END

GO

 (5 row(s) affected)

s

方法一：用户自定义函数

CREATE FUNCTION FN_Merge (@Student NVARCHAR(50))

RETURNS NVARCHAR(50)

AS

      BEGIN

            DECLARE @Course NVARCHAR(50)

            SELECT @Course = ISNULL(@Course + ‘,’,”) + @Course

            FROM SC

            WHERE Student = @Student

            RETURN @COURSE

     END

SELECT DISTINCT [Student]

      ,dbo.FN_Merge([Student]) AS Course

FROM [dbo].[SC]

结果：

(2 row(s) affected)

方法二：FOR XML PATH

SELECT  DISTINCT [Student]

      ,STUFF(

                        (

                              SELECT ‘,’+[Course]

                              FROM [dbo].[SC]

                              WHERE Student = A.Student

                              FOR XML PATH(”)

                        )

                        ,1,1,”

                  )AS Course

  FROM [dbo].[SC] AS A

结果：

(2 row(s) affected)

链接：

1. Stuff（）函数http://msdn.microsoft.com/zh-cn/library/ms188043.asp