Task: Text to Code
Input (English): SQL: SELECT T1.Airline FROM airlines AS T1 WHERE T1.Abbreviation = "CVO" EXCEPT SELECT T1.Airline FROM airlines AS T1 JOIN airports AS T2 WHERE T2.AirportName = "APG"
Feedback: i want source airport, flights and source airport from step 1, 2 and 3 respectively.
Output (English): SELECT T1.Airline FROM AIRLINES AS T1 JOIN FLIGHTS AS T2 ON T1.uid  =  T2.Airline WHERE T2.SourceAirport  =  "CVO" EXCEPT SELECT T1.Airline FROM AIRLINES AS T1 JOIN FLIGHTS AS T2 ON T1.uid  =  T2.Airline WHERE T2.SourceAirport  =  "APG"