我猜 Room.roomID=Reservation.resID 应该是 Room.roomID=Reservation.roomID.

您可以使用子选择尝试不同的方法:

You could try a different approach with a subselect:

SELECT roomID,hotelname,rate 
FROM Room 
WHERE roomID NOT IN (SELECT roomID FROM Reservation WHERE arriveDate >='2010-02-16' and departDate <='2010-02-20')