MySQL query booking system - remove entry if room is already booked

Question

I have been banging my head on this (im a newbie in MySQL, be patient) for two days and i cannot get around this query i want to make... First the data:

I have two tables, one for the rooms like this:

• table ROOMS
• id_room | tipe_room | view_room
• 1.1 | Single | Sea
• 1.2 | Single | Country
• 1.3 | Double | Sea
• 1.4 | Double | Country

• 1.5 | Single | Sea

• table RESERVATIONS

• id_reservation | client_number | n_room | check_in | check_out
• 1 | 1 | 1.1 | 2012-02-20 | 2012-02-24

If a person wants to book a room with tipe_room=Single and view_room=Sea and check_in date=2012-02-15 and check_out date=2012-02-20 i want it to return the id_room available (1.1 and 1.5).

Now if a person wants to book a room with tipe_room=Single and view_room=Sea and check_in date=2012-02-19 and check_out date=2012-02-23 i want it to return the id_room available (only 1.5).

I have been trying around JOIN conditions but when conditions are met it excludes all rooms...

How can I do this, please?

Best Regards, Alex

Answer 1

This query should check for all four cases (A,B,C and D) of occupancy:

  check_in     check_out
      |=TEST=PERIOD=|

  |--A--| |--B--| |--C--|  <- check_in<period_end AND check_out>period_start
    |--------D--------|    <- check_in<period_start AND check_out>period_end

This is complete query:

SELECT `id_room` FROM `rooms` 
WHERE `tipe_room`='Single' AND `view_room`='Sea' 
AND NOT EXISTS 
(
SELECT * FROM `reservations` WHERE `n_room`=`rooms`.`id_room` 
AND ((`check_in`<'2012-02-20' AND `check_out`>'2012-02-15') 
 OR (`check_in`<'2012-02-15' AND `check_out`>'2012-02-20'))
)

Answer 2

Try this Query

select * from room where room.view = :view and room.type = :type
and (select count(*) from reservation r where r.room_id = room.id and 
(r.checkout > :checkin and r.checkin  < :checkout) or
(r.checkin  < :checkin and r.checkout > :checkin))  = 0

The main idea here is to select the room and then check that it is not already booked in the sub select.