--TRY: select a.sid,a.studentname,c.bid from student a inner join (select sid,max(date) date from info group by sid)b on a.sid=b.sid inner join info c on b.sid=c.sid and b.date=c.date
--TRY: select a.sid,a.studentname,c.bid from student a inner join (select sid,max(date) date from info group by sid)b on a.sid=b.sid inner join info c on b.sid=c.sid and b.date=c.date
select a.sid,a.studentname,c.bid from student a inner join (select sid,max(date) date from info group by sid)b on a.sid=b.sid inner join info c on b.sid=c.sid and b.date=c.date
select infor.bid from infor inner join book on infor.bid = book.bid where infor.bookdate in (select max(bookdate) from infor group by sid)
--TRY:
select a.sid,a.studentname,c.bid from student a inner join
(select sid,max(date) date from info group by sid)b on a.sid=b.sid inner join info c
on b.sid=c.sid and b.date=c.date
(select sid,max(date) date from info group by sid)b on a.sid=b.sid inner join info c
on b.sid=c.sid and b.date=c.date
inner join book
on infor.bid = book.bid
where infor.bookdate in
(select max(bookdate) from infor group by sid)