第5次看到这个问题:Select * from StudentAchievement A Where Exists(
select 1 from StudentAchievement
Where CourseID=A.CourseID And Achievement>A.Achievement
Having Count(*)<=1
)
Order by CourseID,Achievement Desc或者:Select *
From StudentAchievement a
Where StudentID in (Select Top 2 StudentID
From StudentAchievement
Where CourseID=a.CourseID
Order by Achievement desc)
order by CourseID,Achievement desc
select 1 from StudentAchievement
Where CourseID=A.CourseID And Achievement>A.Achievement
Having Count(*)<=1
)
Order by CourseID,Achievement Desc或者:Select *
From StudentAchievement a
Where StudentID in (Select Top 2 StudentID
From StudentAchievement
Where CourseID=a.CourseID
Order by Achievement desc)
order by CourseID,Achievement desc
谢谢你的解答
另外请问
Select *
From StudentAchievement a
Where StudentID in (Select Top 2 StudentID
From StudentAchievement
Where CourseID=a.CourseID
Order by Achievement desc)
order by CourseID,Achievement desc
中的思想怎么解释?
特别是Where CourseID=a.CourseID