instruction: list nonstop flights from BWI washington airport to OAKLAND that depart in the afternoon
response: SELECT DISTINCT flight.flight_id FROM airport, airport_service, city, flight WHERE ((airport.airport_code = 'BWI' AND city.city_code = airport_service.city_code AND city.city_name = 'OAKLAND' AND flight.from_airport = airport.airport_code AND flight.to_airport = airport_service.airport_code) AND flight.departure_time BETWEEN 1200 AND 1800) AND flight.stops = 0