简单的查询问题，在线等。。。
declare   @tablename   as   varchar(20)  
select   @tablename   =   (select   top   1   tablename   from   user_temp   )


这样就给@tablename赋值了，
但是如果SQL语句里有变量的话，如何做能把返回值赋给变量呢，
如：select   top   1   tablename   from   user_temp   where   type= '条件 '

------解决方案--------------------
你這裡沒有必要使用動態SQL語句

declare @username as varchar(20)
declare @tablename as varchar(20)
set @username= 'bccu '
select top 1 @tablename =tablename from userinfo where username=@username
select @tablename
------解决方案--------------------
declare @sql as varchar(100)
declare @username as varchar(20)
declare @tablename as varchar(20)
set @username= 'bccu '
set @sql = 'select top 1 @tablename =tablename from userinfo where username= ' ' '+@username+ ' ' ' '
exec sp_executesql @sql,N '@tablename varchar(20) output ',@tablename output
select @tablename
------解决方案--------------------
declare @sql as Nvarchar(100)
declare @username as varchar(20)
declare @tablename as varchar(20)
set @username= 'bccu '
set @sql = N 'select top 1 @tablename =tablename from userinfo where username= ' ' '+@username+ ' ' ' '
exe sp_executesql @sql,N '@tablename varchar(20) output ',@tablename output
select @tablename