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Task 31: 
For each airport, find the average occupancy of flights in August 2017 (according to the actual departure date).
Output the result in two columns departure_airport - departure airport code and average_flights_occupancy - average flight occupancy as a percentage, rounded to two decimal places. 
Sort the results in descending order of the second column. If occupancy values ​​are equal, sort by airport code.

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Use PostgreSQL syntax to write your answer. Descriptions of tables are provided at the bottom of the screen.

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Bookings Database (PostgreSQL)

The subject area of this database is airline flights through various airports. The Bookings Database contains 8 tables.

ER diagram of the Bookings database ER diagram of the Bookings database

The list of tables:

aircrafts_data - table of aircrafts.
  • aircraft_codeUnique code for each aircraft
  • modelAircraft model name in English and Russian in JSON format
  • rangeAircraft fly range in kilometers
  • PRIMARY KEY, btree (aircraft_code)
aircraft_codemodelrange
1773{"en": "Boeing 777-300", "ru": "Боинг 777-300"}11100
airports_data - table of airports.
  • airport_codeUnique code for each airport
  • airport_nameAirport name in English and Russian in JSON format
  • cityAirport city in English and Russian in JSON format
  • coordinatesAirport coordinates as POINT(longitude, latitude)
  • timezoneAirport timezone name
  • PRIMARY KEY, btree (airport_code)
airport_codeairport_namecitycoordinatestimezone
1YKS{"en": "Yakutsk Airport", "ru": "Якутск"}{"en": "Yakutsk", "ru": "Якутск"}(129.77099609375,62.0932998657227)Asia/Yakutsk
boarding_passes - table of boarding passes.
  • ticket_noTicket number
  • flight_idFlight identificator
  • boarding_noBoarding pass number
  • seat_noSeat number
  • PRIMARY KEY, btree (ticket_no, flight_id)
  • UNIQUE CONSTRAINT, btree (flight_id, boarding_no)
  • UNIQUE CONSTRAINT, btree (flight_id, seat_no)
  • FOREIGN KEY (ticket_no, flight_id) REFERENCES ticket_flights(ticket_no, flight_id)
ticket_noflight_idboarding_noseat_no
100054352123513062512D
bookings - table of bookings.
  • book_refBooking number
  • book_dateBooking date
  • total_amountTotal booking cost
  • PRIMARY KEY, btree (book_ref)
book_refbook_datetotal_amount
100000F2017-07-05 00:12:00+00265700.00
flights - table of flights.
  • flight_idFlight ID
  • flight_noFlight number
  • scheduled_departureScheduled departure time
  • scheduled_arrivalScheduled arrival time
  • departure_airportAirport of departure
  • arrival_airportAirport of arrival
  • statusFlight status
  • aircraft_codeAircraft code, IATA
  • actual_departureActual departure time
  • actual_arrivalActual arrival time
  • PRIMARY KEY, btree (flight_id)
  • UNIQUE CONSTRAINT, btree (flight_no, scheduled_departure)
flight_id flight_no scheduled_departure scheduled_arrival departure_airport arrival_airport status aircraft_code actual_departure actual_arrival
11185PG01342017-09-10 06:50:00+002017-09-10 11:55:00+00DMEBTKScheduled319
seats - table of aircraft seats.
  • aircraft_codeAircraft code, IATA
  • seat_noSeat number
  • fare_conditionsTravel class
  • PRIMARY KEY, btree (aircraft_code, seat_no)
  • FOREIGN KEY (aircraft_code) REFERENCES aircrafts(aircraft_code) ON DELETE CASCADE
aircraft_codeseat_nofare_conditions
13192ABusiness
ticket_flights - ticket to flights relations.
  • ticket_noTicket number
  • flight_idFlight ID
  • fare_conditionsTravel class
  • amountTravel cost
  • PRIMARY KEY, btree (ticket_no, flight_id)
  • FOREIGN KEY (flight_id) REFERENCES flights(flight_id)
  • FOREIGN KEY (ticket_no) REFERENCES tickets(ticket_no)
ticket_no flight_id fare_conditions amount
1000543215977630625Business42100.00
tickets - table of tickets.
  • ticket_noTicket number
  • book_refBooking number
  • passenger_idPassenger ID
  • passenger_namePassenger name
  • contact_dataPassenger contact information
ticket_no book_ref passenger_id passenger_name contact_data
1000543200098706B0468149 604011VALERIY TIKHONOV{"phone": "+70127117011"}
  • PRIMARY KEY, btree (ticket_no)
  • FOREIGN KEY (book_ref) REFERENCES bookings(book_ref)
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SQL in 10 Minutes a Day by Ben Forta
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