CREATE TABLE stadium (id DECIMAL, name TEXT, capacity DECIMAL, city TEXT, country TEXT, opening_year DECIMAL)
CREATE TABLE record (id DECIMAL, result TEXT, swimmer_id DECIMAL, event_id DECIMAL)
CREATE TABLE swimmer (id DECIMAL, name TEXT, nationality TEXT, meter_100 DECIMAL, meter_200 TEXT, meter_300 TEXT, meter_400 TEXT, meter_500 TEXT, meter_600 TEXT, meter_700 TEXT, time TEXT)
CREATE TABLE event (id DECIMAL, name TEXT, stadium_id DECIMAL, year TEXT)

Which country has both stadiums with capacity greater than 60000 and stadiums with capacity less than 50000?
SELECT country FROM stadium WHERE capacity > 60000 INTERSECT SELECT country FROM stadium WHERE capacity < 50000
SELECT "country" FROM "stadium" WHERE "capacity" > 60000 INTERSECT SELECT "country" FROM "stadium" WHERE "capacity" < 50000