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The Cancellation Rate

mediumSQLCASEArithmetic

The UrbanHop board does not want the number of cancellations, it wants the proportion — three cancellations means one thing in a city doing twelve bookings and something else entirely in a city doing twelve hundred. The figure they track is the share of everything booked that ended up cancelled, as a percentage, to one decimal place.

Everything booked is the denominator: completed and cancelled together, since the question is what fraction of demand the platform failed to serve.

rides — one row per booking. rider_id points at a row in riders and driver_id at a row in drivers. distance_km is the trip length in kilometres and fare the price in dollars; both are recorded when the booking is made, so a booking that never happened still carries them. status is either completed or cancelled. ride_date is the day the ride was booked for.

id rider_id driver_id distance_km fare ride_date status
1 1 1 5.2 12.5 2023-06-01 completed
2 1 4 3.0 8.0 2023-06-03 completed
3 2 2 10.0 22.0 2023-06-02 completed
4 3 1 2.1 6.5 2023-06-05 cancelled
5 3 4 4.4 11.0 2023-06-06 completed
6 4 3 7.8 18.0 2023-06-04 completed
7 5 2 1.5 5.0 2023-06-07 cancelled
8 2 2 12.3 26.5 2023-06-10 completed
9 1 1 6.6 15.0 2023-06-12 completed
10 4 3 3.3 9.0 2023-06-15 completed
11 5 2 8.8 19.5 2023-06-18 completed
12 3 4 2.9 7.5 2023-06-20 cancelled

The table already exists in the database — there is nothing to create or load.

Task: Write a query that returns one row with one column, cancel_rate_pct, holding cancelled bookings as a percentage of all bookings, rounded to one decimal place.

Example output

If two bookings in five had fallen through, the single row would read — note that a whole percentage comes back as 40, not 40.0:

cancel_rate_pct
40

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