เที่ยวบินทั้งหมดจากบอสตันไปพิตส์เบิร์กในวันพุธมีอะไรบ้าง ไม่จำเป็นที่จะต้องใช้ตารางทั้งหมด
what are all flights from BOSTON to PITTSBURGH on WEDNESDAYIt 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, days, flight WHERE (CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'PITTSBURGH' AND days.day_name = 'WEDNESDAY' AND flight.flight_days = days.days_code AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'BOSTON' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code