For each room, count how many times it was booked.
select count(*) from reservations group by room
Which rooms have been booked more than 60 times?
select * from reservations as t1 join rooms as t2 on t1.room = t2.roomid group by t1.room having count(*) > 60
Give me the names of the rooms.
select t2.roomname from reservations as t1 join rooms as t2 on t1.room = t2.roomid group by t1.room having count(*) > 60