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

Find the names of stadiums which have never had any event.
SELECT name FROM stadium WHERE NOT id IN (SELECT stadium_id FROM event)
SELECT "name" FROM "stadium" WHERE NOT "id" IN (SELECT "stadium_id" FROM "event")