Select only rows by join tables max value

Question

I want to select only the row which has max b.enddate for u.classno, u.userno. But it doesn\'t work.

select u.classno, u.userno, b.enddate
from libUser u
joi         


        

Answer 1

Whats wrong with:

select u.classno, u.userno, MAX(b.enddate)
from libUser u
join book b on b.id = u.bookid
group by u.classno, u.userno