Can you try this?DECLARE @Checkin DATETIME, @Checkout DATETIME;
SET @CheckIn = '20130201';
SET @Checkout = '20130207';
SELECT
h.HotelID
FROM
Hotels h
WHERE
NOT EXISTS
(
SELECT * FROM BookedDays b
WHERE b.HotelId = h.HotelId
AND b.BookedDate BETWEEN @CheckIn AND @CheckOut
);