What are the names of all the pilots who flew a flight in the Billund Airport?
SELECT DISTINCT T2.pilot FROM airport AS T1 JOIN flight AS T2 ON T1.id   =   T2.airport_id WHERE T1.name  =  'Billund Airport'
names of all the pilots = SELECT DISTINCT pilot; who flew a flight in the Billund Airport = WHERE airport.name = 'Billund Airport'; joining tables to match flights with the specific airport = JOIN flight ON airport.id = flight.airport_id;