sqlserver字符串多行合并为一行

 --创建测试表
 CREATE TABLE [dbo].[TestRows2Columns](
     [Id] [int] IDENTITY(,) NOT NULL,
     [UserName] [nvarchar]() NULL,
     [Subject] [nvarchar]() NULL,
     [Source] [numeric](,) NULL
 )
 GO

 --插入测试数据
 INSERT INTO [TestRows2Columns] ([UserName],[Subject],[Source])
     SELECT N'张三',N'语文',  UNION ALL
     SELECT N'李四',N'数学',  UNION ALL
     SELECT N'王五',N'英语',  UNION ALL
     SELECT N'王五',N'数学',  UNION ALL
     SELECT N'王五',N'语文',  UNION ALL
     SELECT N'李四',N'语文',  UNION ALL
     SELECT N'张三',N'英语',
 GO

 SELECT * FROM [TestRows2Columns]

 -- 通过 select 累加
 DECLARE @sql_col VARCHAR()
 SELECT @sql_col = ISNULL(@sql_col + ',','') + QUOTENAME([Subject]) FROM TestRows2Columns
 GROUP BY [Subject]

 SELECT @sql_col

 -- 通过 FOR xml path('') 合并字符串记录
 SELECT
     STUFF(
         (SELECT '#' + Subject
          FROM TestRows2Columns
          WHERE UserName = '王五'
          FOR xml path('')
         ),,,''
         )

 -- 分组合并字符串记录
 SELECT
     UserName,
     Subject = (
                STUFF(
                     (SELECT '#' + Subject
                      FROM TestRows2Columns
                      WHERE UserName = A.UserName
                      FOR xml path('')
                     ),,,''
                     )
                  )
 FROM TestRows2Columns A
 GROUP by UserName