using mysql stored-function with select query - php

Question

let me explain my purpose first, i have an vehicle booking application where, visitor will add start date and end date of his journey, in the database there is list of drivers with there availability (available_from_date and available_to_date) which is kind of duration during which they are operating, there is an field for exclude_dates for some specific dates when they are not working.
the application needs to find a list of vehicles which are available during the journey dates entered by the user.
for example user enters he want to go from place A to B during 13th sept, 2014 to 17th sept, 2014
then database needs to return a list of taxi which are available during this period and must not have any exclude date within this period.
Now i have stored the exclude_dates in comma separated format in table (i could have created a separate table but then it would take much more time for a query to execute)
I was trying to create a mysql function which would be called within the actual search query and would return true if there is some there is some excluded date present within the duration and false if not.
these are the queries that i have written
SELECT id, exclude_dates
FROM `taxi_route`
WHERE status = 1
AND `to_city` = 'Surat'
AND `from_city` = 'Ahmedabad'
AND `trip_type` = 2
AND `available_from_date` <= '2014-09-13'
AND available_to_date >= '2014-09-17'
AND STR_TO_DATE((SELECT `split`(exclude_dates, ',', 1)),'%d-%m-%Y')
NOT BETWEEN STR_TO_DATE('13-09-2014','%d-%m-%Y')
AND STR_TO_DATE('17-09-2014','%d-%m-%Y')
Split is a function i have created in mysql to separate the dates present in comma format
DELIMITER $$
CREATE FUNCTION split( str VARCHAR(500), delchar VARCHAR(2), x INT )
RETURNS VARCHAR(500)
BEGIN
RETURN SUBSTR(SUBSTRING_INDEX(str, delchar, x),
LENGTH(SUBSTRING_INDEX(str, delchar, x-1))+IF(x > 1, 2, 1));
END$$
DELIMITER ;
this works fine as far as i pass 1 in split(exclude_dates, ',', 1) , but if the exclude_dates have more then one date then this will not work
can someone please suggest or guide, how this can be accomplished.
snapshot of database is here http://i.imgur.com/JaI8MSx.png

Answer 1

Your query is most likely going to take more time to execute than defining a separate table for exclusion dates. It's not a good practice using comma separated list inside a column for searching purposes, this is against normalization rules.
You should define your tables separately, (e.g. taxi, taxi_route, taxi_route_exclusion, route_exclusion) and later add necessary indexes to make your searches more efficient.
Example:
taxi
---------
id
country
***
***
***
taxi_route
-------------------
id
taxi_id
available_from_date
available_to_date
from_city
to_city
route_exclusion
---------------
id
taxi_id
exclusion_date
And also add a relation table between taxi_route and route_exclusion tables to represent many-to-many relationship. Later define foreign keys on taxi_route_route_exclusion table to point taxi_route and route_exclusion tables.
taxi_route_route_exclusion
--------------------------
taxi_route_id
route_eclusion_id
Define foreign keys like:
taxi_route.taxi_id -> taxi.id
taxi_route_route_exclusion.taxi_route_id -> taxi_route.id
taxi_route_route_exclusion.route_exclusion_id -> route_exclusion.id
Define indexes like:
taxi: IX1 (status, trip_type)
taxi_route: IX1(to_city, from_city, available_from_date, available_to_date)
Your final query should look like this:
SELECT tr.id, re.exclusion_date
FROM `taxi_route` tr JOIN `taxi_route_route_exclusion` trre
ON tr.id = trre.taxi_route_id
JOIN `route_exclusion` re
ON re.id = trre.route_exclusion_id
JOIN `taxi` t
ON t.id = tr.id
WHERE
t.status = 1
AND t.trip_type = 2
AND tr.to_city = 'Surat'
AND tr.from_city = 'Ahmedabad'
AND tr.available_from_date <= '2014-09-13'
AND tr.available_to_date >= '2014-09-17'