What is the block floor each room is located on?
select t1.blockfloor from block as t1 join room as t2 on t1.blockfloor = t2.blockfloor and t1.blockcode = t2.blockcode
How many rooms does each block floor have?
select count(*), t1.blockfloor from block as t1 join room as t2 on t1.blockfloor = t2.blockfloor and t1.blockcode = t2.blockcode group by t1.blockfloor