动态SQL列转行问题
CREATE TABLE [dbo].[test1](
[id] [int] NULL,
[name] [varchar](50) NULL,
[class] [varchar](20) NULL
) ON [PRIMARY]
GO
insert into test1 values
(1 ,'a1' ,54),
(2 ,'a2' ,88),
(3 ,'a3',88),
(4 ,'a4',53)
declare @sql nvarchar(max)
select @sql=isnull(@sql+',','') + quotename([id]) from table1
print @sql
结果
--------------------------------------------
[a1],[a2],[a3],[a4]
求教 怎么理解 select @sql=isnull(@sql+',','') + quotename([name]) from table1
为什么 输出值= [a1],[a2],[a3],[a4]