มีการขนส่งใดบ้างจากสนามบินดัลลาสไปยังตัวเมืองไม่จำเป็นต้องใช้ตารางทั้งหมด
what transportation is available from the DALLAS airport to downtownIt is not neccessary to use all the tables.
 city:  city_code [ varchar]  city_name [ varchar]  state_code [ varchar]  country_name [ varchar]  time_zone_code [ varchar] 
SELECT DISTINCT ground_service.transport_type FROM airport, airport_service, city AS CITY_0, city AS CITY_1, ground_service WHERE airport.airport_code = airport_service.airport_code AND CITY_0.city_code = airport_service.city_code AND CITY_0.city_name = 'DALLAS' AND CITY_1.city_name = 'DALLAS' AND ground_service.airport_code = airport.airport_code AND ground_service.city_code = CITY_1.city_code