Dear all

Thank you all for spending your time in this topic, and now, i've finished this problem by following code:

select distinct [Subject].SubName, Marks.Mark from Marks

inner join [Subject] on Marks.SubID=[Subject].SubID

where Marks.Mark in(select MAX(Marks.Mark)as diem from Marks group by Marks.SubID )

Thank all again for your help! I am so lucky wheng joining this 4rum