Room Booking Query

Question

I have a problem in writing the sql to get the availables rooms from the tables.

My tables structures are given below.

Table Booking
ID | START_DATE         


        

Answer 1

You'll want to define a clear recordsets for "all bookings made on day X", and then use an outer join to retrieve those rooms that don't have a booking for said day.

SET @myDate = #someDay#
SELECT R.ID
FROM Room R
WHERE R.ID NOT IN (
    SELECT BR.ROOM_ID
    FROM BookingRoom BR
    INNER JOIN Booking B ON BR.Booking_ID = B.ID
    WHERE @myDate BETWEEN B.start_date and B.end_date
)

Edit:

Since you want ALL open rooms during a reservation, you'll need to do a more complicated query. I'll assume that you already have the dates in question loaded outside, since doing a date-based many-to-many query is a PITA.

SET @dateStart = #Start#
SET @dateEnd = #End#

SELECT R.ID
FROM Room R
WHERE R.ID NOT IN (
    SELECT BR.ROOM_ID
    FROM BookingRoom BR
    INNER JOIN Booking B ON BR.Booking_ID = B.ID
    WHERE B.start_date BETWEEN @dateStart AND @dateEnd
    AND B.end_date BETWEEN @dateStart AND @dateEnd
)

Answer 2

If all you want is the list of rooms available for the entire range of desired dates, then something like the following might work:

Select Room.Id
From Room
Where Room.Id Not In    (
                        Select RoomId
                        From BookingRoom
                            Join Booking
                                On Booking.Id = BookingRoom.BookingId
                        Where Booking.StartDate <= 'DesiredEndDate'
                            And Booking.EndDate >= 'DesiredStartDate'
                        )
Order By Room.Id

So, using the original example, we might get:

Select Room.Id
From Room
Where Room.Id Not In    (
                        Select RoomId
                        From BookingRoom
                            Join Booking
                                On Booking.Id = BookingRoom.BookingId
                        Where Booking.StartDate <= '2013-05-15'
                            And Booking.EndDate >= '2013-05-14'
                        )
Order By Room.Id