create function average(@cnum char(20)) returns int as begin declare @aver int select @aver=avg(成绩) from xscj where 课程编号=@cnum return @aver end ---- declare @course1 char(20) declare @aver1 int select @aver1=dbo.average(@course1) select @aver1 as '104课程的平均成绩'