Time Gap Between Departures | Dataford Interview Questions

Given a table of flight departures, write a query using window functions (LEAD or LAG) to find the time difference between consecutive departures from the same airport.

Use the provided flight_departures table. Ignore rows with a NULL airport code or departure time, and exclude each airport's final departure because it has no following departure.

Output

One row per departure with a following departure at the same airport
Columns: airport_code, departure_id, departure_time, next_departure_time, and minutes_to_next
Order by airport code, departure time, and departure ID; use departure ID to break ties

Schema

flight_departures

Column	Type	Description
departure_idPK	INTEGER	Unique identifier for the departure
airport_code	VARCHAR(3)	Three-letter airport code
departure_time	TIMESTAMP	Scheduled departure timestamp

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