sql妙用,输出参数

declare   @num int,
@num1 nvarchar(30),
@sqls nvarchar(4000)  
set @sqls='select @a=FeeID,@b=ItemID from FeeItems'  
exec sp_executesql @sqls,N'@a int output,@b nvarchar output',@num output  ,@num1 output
select @num,@num1