MySQL Expert Required!! Advanced Query Problem

Question

I am currently developing a hotel booking system for my University final year project and am having some serious problems with my query to calculate room availability.
I felt the best method to calculate room availability was to first calculate which rooms were already booked for any specific queried dates and then to subtract those results from the list of total rooms. That would then return which rooms were available on those dates.
However the query that I am using to calculate which rooms are already booked is very inefficient, in that, for example,
A booking which is for more than one night can overlap the date you are testing for availability. It's even worse when you check the availability of rooms for multiple nights. My query does not cover those scenarios.
If anyone can help me solve this problem or suggest alternative methods I would be most appreciative.
Below is the MySQL code for the relevant parts of my database, and the query that I am currently using.
Thanks!
CREATE TABLE booking
booking_id               INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
e_mail                VARCHAR(40) NOT NULL REFERENCES guestdetails(e_mail),
arrival_date          DATE NOT NULL,
departure_date          DATE NOT NULL,
PRIMARY KEY(booking_id)
CREATE TABLE roombooked
booking_id               INTEGER UNSIGNED NOT NULL REFERENCES booking(booking_id),
room_id               INTEGER UNSIGNED NOT NULL REFERENCES rooms(room_no),
no_of_nights          INTEGER UNSIGNED NOT NULL,
PRIMARY KEY(booking_id,room_id)
CREATE TABLE rooms
room_no               INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
room_name           VARCHAR(11),
room_type               VARCHAR(9),
single_price          DECIMAL(5,2),
double_price          DECIMAL(5,2),
PRIMARY KEY(room_no)
insert into rooms (room_name,room_type,single_price,double_price)
values ('shakespeare','principal','165','225'),
('keats','principal','165','225'),
('kipling','standard','125','165'),
('tennyson','superior','135','185'),
('shelley','deluxe','155','205'),
('brooke','superior','135','185'),
('wordsworth','deluxe','155','205'),
('milton','deluxe','155','205'),
('masefield','deluxe','155','205'),
('browning','deluxe','155','205');
///ROOM AVAILABILITY QUERY///
CREATE TEMPORARY TABLE roomsoccupied          
SELECT roombooked.room_id FROM roombooked, booking
WHERE
roombooked.booking_id = booking.booking_id
AND
booking.arrival_date <= 'QueriedArrivalDate'
AND
booking.departure_date >= 'QueriedDepartureDate';

Answer 1

Yes, it does solve your problem.
For example, if you have a room that is booked from the 1st - 4th and then receive an availability query for the 2nd - 6th my current query would not detect that, that particular room is already booked on those dates.
So, 'QueriedArrivalDate = 2 and 'QueriedDepartureDate' = 6
Now, let see the query
CREATE TEMPORARY TABLE roomsoccupied
SELECT roombooked.room_id FROM roombooked, booking
WHERE
roombooked.booking_id = booking.booking_id
AND
booking.arrival_date < 'QueriedDepartureDate'
AND
booking.departure_date > 'QueriedArrivalDate';
yes, it will detect it becuase 1 < 6 and 4 > 2
Please look at it better, it not only solves your current problem scenario but other scenarios like if the book is 2 - 7 and the request is 3 - 5 etc etc.