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CREATE TABLE bookings
(`ID` int, `arrival_date` date, `departure_date` date, `price_per_night` int)
;
INSERT INTO bookings
(`ID`, `arrival_date`, `departure_date`, `price_per_night`)
VALUES
(1, '2023-01-29")', '2023-02-02', 50)
;
SELECT SUM((DATEDIFF(departure_date,arrival_date) - 1) * `price_per_night`) sum_price
FROM `bookings`
WHERE MONTH(arrival_date) = 1
| sum_price |
|---|
| 150 |