SELECT SUM(price) AS IncomeLost FROM (
	SELECT Room.roomNo, Room.hotelNo, Room.price
	FROM Room
	GROUP BY Room.roomNo, Room.hotelNo, Room.price
	MINUS
	SELECT Room.roomNo, Room.hotelNo, Room.price
	FROM Room
	INNER JOIN Booking
	ON Booking.roomNo = Room.roomNo
	WHERE Booking.dateFrom <= '2015-02-01' AND (Booking.dateTo >= '2015-02-01' OR Booking.dateTo IS NULL)
)
GROUP BY hotelNo;


-----------Trying to join it to get HotelName-----------
SELECT Hotel.hotelNo, Hotel.hotelName, SUM(price) AS IncomeLost FROM (
	SELECT Room.roomNo, Room.hotelNo, Room.price
	FROM Room
	GROUP BY Room.roomNo, Room.hotelNo, Room.price
	MINUS
	SELECT Room.roomNo, Room.hotelNo, Room.price
	FROM Room
	INNER JOIN Booking
	ON Booking.roomNo = Room.roomNo
	WHERE Booking.dateFrom <= '2015-02-01' AND (Booking.dateTo >= '2015-02-01' OR Booking.dateTo IS NULL)
)
INNER JOIN Hotel
ON Hotel.hotelNo = hotelNo
GROUP BY hotelNo;