เที่ยวบินใดจากนิวยอร์กไปลอสแองเจลิสไม่จำเป็นต้องใช้ตารางทั้งหมด
what flights from NEW YORK to LOS ANGELESIt is not neccessary to use all the tables.
 fare:  fare_id [ int]  from_airport [ varchar]  to_airport [ varchar]  fare_basis_code [ text]  fare_airline [ text]  restriction_code [ text]  one_direction_cost [ int]  round_trip_cost [ int]  round_trip_required [ varchar] 
SELECT DISTINCT flight.flight_id FROM airport_service AS AIRPORT_SERVICE_0, airport_service AS AIRPORT_SERVICE_1, city AS CITY_0, city AS CITY_1, flight WHERE CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'NEW YORK' AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'LOS ANGELES' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code AND flight.to_airport = AIRPORT_SERVICE_1.airport_code