Table schema:
CREATE TABLE AIRLINES (Airline VARCHAR, uid VARCHAR); CREATE TABLE FLIGHTS (Airline VARCHAR, SourceAirport VARCHAR)

Question: What are airlines that have some flight departing from airport 'AHD'?
SQL: SELECT T1.Airline FROM AIRLINES AS T1 JOIN FLIGHTS AS T2 ON T1.uid = T2.Airline WHERE T2.SourceAirport = "AHD"