Find the names of stadiums that the least swimmers have been to?
select t3.name from record as t1 join event as t2 on t1.event_id = t2.id join stadium as t3 on t3.id = t2.stadium_id group by t2.stadium_id order by count ( * ) desc limit 1
How many events in this table?
select count ( name ) from event
How many stadiums in this table?
select count ( name ) from stadium