คุณมีเที่ยวบินช่วงเช้าระหว่าง OAKLAND และ DENVER กี่เที่ยวไม่จำเป็นต้องใช้ทุกตาราง
what morning flights do you have between OAKLAND and DENVERIt is not neccessary to use all the tables.
 dual_carrier:  main_airline [ varchar]  low_flight_number [ int]  high_flight_number [ int]  dual_airline [ varchar]  service_name [ text] 
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 = 'OAKLAND' AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'DENVER' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND flight.departure_time BETWEEN 0 AND 1200