เที่ยวบินจาก PHOENIX ไปยัง NEWARKI ไม่จำเป็นต้องใช้ตารางทั้งหมด
flights from PHOENIX to NEWARKIt is not neccessary to use all the tables.
 time_zone:  time_zone_code [ text]  time_zone_name [ text]  hours_from_gmt [ int] 
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 = 'PHOENIX' AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'NEWARK' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code AND flight.to_airport = AIRPORT_SERVICE_1.airport_code