Dropdown with union query - mysql

Question

I'm developing a booking system and in my booking form I have a dropdown element which is returning (still) available start time slots for a booking system.
By creating a new booking the query I have created is working fine and all available start time slots are returned correctly.
QUERY :
WHERE {thistable}.id
IN (
SELECT id +3
FROM (
SELECT p1.book_date, t.*, count(p1.book_date) AS nbre
FROM fab_booking_taken AS p1
CROSS JOIN fab_booking_slots AS t
WHERE NOT ((t.heuredepart_resa < p1.book_end AND
t.heurearrivee_resa > p1.book_start))
AND DATE(p1.book_date)=DATE('{fab_booking___book_bookingdate}')
GROUP BY t.id) AS x
WHERE nbre =
(
SELECT count(p2.book_date)
FROM fab_booking_taken AS p2
WHERE p2.book_date = x.book_date
)
) ORDER BY id ASC
Please see video : booking creationg
The problem I have by using the same query by editing an existing booking the available start time slots are returned which is fine :
18:00
18:30
19:00
19:30
but not the already by the customer chosen (and in the database saved) time slot which is in my example 14:00.
Please see video : Editing booking with same query
Dropdown should be populated with the following options :
14:00
18:00
18:30
19:00
19:30
I tried to create an union query to get the already by the customer chosen start time slot and the (still) available start time slots.
QUERY :
{thistable}.id
IN (
SELECT id + 3
FROM (
SELECT p1.book_date, t.*, count(p1.book_date) AS nbre
FROM fab_booking_taken AS p1
CROSS JOIN fab_booking_slots AS t
WHERE NOT ((t.heuredepart_resa < p1.book_end
AND t.heurearrivee_resa > p1.book_start))
AND p1.book_date = DATE_FORMAT('{fab_booking___book_bookingdate}', '%Y-%m-%d')
GROUP BY t.id
) as foobar2
UNION (
SELECT id + 3
FROM (
SELECT p1.book_date, t.*, count(p1.book_date) AS nbre
FROM fab_booking_taken AS p1
CROSS JOIN fab_booking_slots AS t
WHERE ( ( t.heuredepart_resa < p1.book_end
AND t.heurearrivee_resa > p1.book_start ) )
AND t.id = '{fab_booking___book_starttime}'
AND p1.book_date = DATE_FORMAT('{fab_booking___book_bookingdate}', '%Y-%m-%d')
GROUP BY t.id
) AS x
WHERE nbre = (
SELECT count(p2.book_date)
FROM fab_booking_taken AS p2
WHERE p2.book_date = x.book_date
)
)
)
The already by the customer chosen start time slot is returned (14:00) but the other available returned start time slots are not correct.
Please see video : Editing booking with union query
I'm stuck and I have no clue how I could solve this issue, so I would appreciate some help here.
Thanks
Relevant database tables
fab_booking with the booking concerned into the video
please download the sql table
fab_booking_taken with the already existing bookings on 25 11 2016 id = 347
Please download the sql table
id 347 is the concerned booking
fab_booking_slots table which contains all possible time slots
Please download the sql table
fab_heuredepart_resa table which populate the dropdown element
Please download the sql table

Answer 1

I have to admit that it is daunting to try to untangle that query to understand the logic behind it but I think that the following query should return the results that you need.
{thistable}.id IN (
/*Finds booking slots where the booking slot does not overlap
with any of the existing bookings on that day,
or where the booking slot id is the same as the current slot.*/
SELECT t.id + 3
FROM fab_booking_slots AS t
WHERE t.id = '{fab_booking___book_starttime}'
OR NOT EXISTS (
Select 1
From fab_booking_taken AS p1
Where Date(p1.book_date) = Date('{fab_booking___book_bookingdate}')
And p1.book_end > t.heuredepart_resa
And p1.book_start < t.heurearrivee_resa
)
)
Order By id Asc;
I'm pretty sure that this is logically equivalent, and once expressed in a simplified form like this it's easier to see how you can get it to also return the additional time slot.
You should have a separate query to use when populating the time slots for a new booking that doesn't have an existing time slot, in which case you can just remove the single line t.id = '{fab_booking___book_starttime}' OR.