What is the minimum number of rooms for the apartments?
select min(room_count) from apartments
List all the short names of each building.
select building_short_name from apartment_buildings
For each short name, show the room count.
select t1.building_short_name, t2.room_count from apartment_buildings as t1 join apartments as t2 on t1.building_id = t2.building_id
Only keep the result of "Columbus Square".
select sum(t2.room_count) from apartment_buildings as t1 join apartments as t2 on t1.building_id = t2.building_id where t1.building_short_name = "Columbus Square"