SELECT count(*) ,  class_room FROM CLASS GROUP BY class_room HAVING count(*)  >=  2
Find the number of classes offered for all class rooms that held at least 2 classes.
SELECT count ( * ) , class_room FROM CLASS GROUP BY class_room HAVING count ( * ) > = 2
select count ( * ) , class_room from class group by class_room having count ( * ) > = value
Find the number of classes offered for all class rooms that held at least 2 classes .