Task: Text to Code
Input (English): Step 1: For each row in airports table, find the corresponding rows in flights table.
Step 2: find AirportCode of the results of step 1 with largest value of FlightNo
Output (English): SELECT T1.AirportCode FROM airports AS T1 JOIN flights AS T2 ON T1.AirportCode = T2.SourceAirport ORDER BY T2.FlightNo Desc LIMIT 1