Flights schema/database: Find all airports that have no flights from them in the flight database. ( using sql/92 syntax join)

fk airline (fk) country region airline_id_iata radio_callsign country airline_name iso_code country_name iso_code country_code airport (fk icao_identifier airport_typeairport_ name latitude longitude elevation region municipality (fk) (fk) (fk) route airline_id_iata departure_airport_icao arrival_airport_icao codeshare stops K) runway equipment airport_icao end_one_identifier length_ft lighted airline_id dep_airport arr_airport aircraft_type