เที่ยวบินชั้นหนึ่งที่มีให้บริการจากเดนเวอร์ไปยังบัลติมอร์ในวันที่ 7 25 1991 ไม่จำเป็นที่จะต้องใช้ตารางทั้งหมด
what FIRST class flights are available from DENVER to BALTIMORE on 7 25 1991It is not neccessary to use all the tables.
 fare_basis:  fare_basis_code [ text]  booking_class [ text]  class_type [ text]  premium [ text]  economy [ text]  discounted [ text]  night [ text]  season [ text]  basis_days [ 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, date_day AS DATE_DAY_0, date_day AS DATE_DAY_1, days AS DAYS_0, days AS DAYS_1, fare, fare_basis AS FARE_BASIS_0, fare_basis AS FARE_BASIS_1, flight, flight_fare WHERE ((DATE_DAY_0.day_number = 25 AND DATE_DAY_0.month_number = 7 AND DATE_DAY_0.year = 1991 AND DATE_DAY_1.day_number = 25 AND DATE_DAY_1.month_number = 7 AND DATE_DAY_1.year = 1991 AND DAYS_0.day_name = DATE_DAY_0.day_name AND DAYS_1.day_name = DATE_DAY_1.day_name AND FARE_BASIS_0.class_type = 'FIRST' AND FARE_BASIS_1.basis_days = DAYS_1.days_code AND fare.fare_basis_code = FARE_BASIS_0.fare_basis_code AND fare.fare_basis_code = FARE_BASIS_1.fare_basis_code AND flight_fare.fare_id = fare.fare_id AND flight.flight_days = DAYS_0.days_code AND flight.flight_id = flight_fare.flight_id) AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'BALTIMORE' AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'DENVER' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code