Table schema:
CREATE TABLE AIRPORTS (AirportCode VARCHAR, City VARCHAR); CREATE TABLE AIRLINES (uid VARCHAR, Airline VARCHAR); CREATE TABLE FLIGHTS (DestAirport VARCHAR, Airline VARCHAR)

Question: How many United Airlines flights go to City 'Aberdeen'?
SQL: SELECT COUNT(*) FROM FLIGHTS AS T1 JOIN AIRPORTS AS T2 ON T1.DestAirport = T2.AirportCode JOIN AIRLINES AS T3 ON T3.uid = T1.Airline WHERE T2.City = "Aberdeen" AND T3.Airline = "United Airlines"