มีสายการบินใดบ้างที่มีเที่ยวบิน JET ระหว่างพิตส์เบิร์กและบัลติมอร์ ไม่จำเป็นต้องใช้ตารางทั้งหมด
does any airline have a JET flight between PITTSBURGH and BALTIMOREIt is not neccessary to use all the tables.
 ground_service:  city_code [ text]  airport_code [ text]  transport_type [ text]  ground_fare [ int] 
SELECT DISTINCT flight.flight_id FROM aircraft, airport_service AS AIRPORT_SERVICE_0, airport_service AS AIRPORT_SERVICE_1, city AS CITY_0, city AS CITY_1, equipment_sequence, flight WHERE (aircraft.propulsion = 'JET' AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'BALTIMORE' AND equipment_sequence.aircraft_code = aircraft.aircraft_code AND flight.aircraft_code_sequence = equipment_sequence.aircraft_code_sequence AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'PITTSBURGH' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code