一个很简单的用户自定义函数!

create function GetParentID (@ID int)
returns int
as
Begin
Declare @pid int
set @pid =0
select @pid = classparentid from uds_class where classid = @id
return @pid
End

转载于:https://www.cnblogs.com/lingxzg/archive/2006/07/18/453480.html