Question

The table below shows a small database whose records correspond to flights departing from an airport. (a). Are the attributes "Airline" and "Destination" a key for this database? (b). Give two examples of sets of attributes that are keys for this database. (c). Show the results of Select [Airlines = "JetGreen" and Destination = "Denver"]. (d). Show the results of Project [Airline, = "Gate]. (e). Show the results of Select [Destination = "Denver"] followed by Project Gate (f). What operations should be performed if you want to know which airlines use gate 22? (g). What operations should be performed if you want to know whether there are any flights to Detroit departing before 09:10? A flight is identified by the airline and flight number.

Answer 1

a. No because because composite key (Airline, Destination) have duplicate Answer b. 1) (Airline, flightNumber) 2)(FlightNumber, Destination) Answer c. Airline FlightNumber Gate Destination DepartureTime JetGreen 221 22 Denvar 08: 17 JetGreen 222 22 Denvar 09: 10 Answer d. Airline Gate FlyRight 34 JetGreen 22 JetGreen 33 JetGreen 34 FlyRight 13 JetGreen 22 FlyRight 34 Answer e. Airline Gate JetGreen 22 JetGreen 22 Answer f. Select [Airline] followed by project [Gate = 22] Answer g. Select [Airline, Flight Number] followed by project [Departure < 09: 10]