MySQL NOT IN function of array of data - php

Question

This is my query. Using WHERE IN works normally in the MySQL GUI, however, when I run this query, it returns an empty result. I have checked them manually if the dates exist in the events table, and they really do.
SELECT * FROM venues v
LEFT JOIN reservations r ON v.venue_id = r.venue_id
LEFT JOIN events e ON e.reservation_id = r.reservation_id
WHERE e.date_of_use NOT IN ('$dates')
$dates is just a string of dates (i.e., 11-11-2018, 11-12-2018).

Answer 1

There is an error in the $dates string.
It should be formatted as '11-11-2018', '11-12-2018' i.e. each value should be enclosed in quotes to make IN query work.
Currently, your query looks like
WHERE e.date_of_use NOT IN ('11-11-2018, 11-12-2018');
which will search for rows with 2 dates instead of single dates.
Here's how a correct query would look like,
SELECT * FROM venues v
JOIN reservations r ON v.venue_id = r.venue_id
JOIN events e ON e.reservation_id = r.reservation_id
WHERE e.date_of_use NOT IN ('11-11-2018', '11-12-2018')
Update 1
Based on your comment, you have to implode the array with ','.
$dates = implode( "','", $date );
And then the below WHERE clause will work perfect,
WHERE e.date_of_use NOT IN ('$dates')
Update 2
If events and reservations tables are empty, then you need to use LEFT JOIN and fetch rows where date_of_use IS NULL
SELECT * FROM venues v
LEFT JOIN reservations r ON v.venue_id = r.venue_id
LEFT JOIN events e ON e.reservation_id = r.reservation_id
WHERE e.date_of_use NOT IN ('$dates')
OR e.date_of_use IS NULL

Answer 2

If $dates variable as you say, is a string with comma separated dates "11-11-2018, 11-12-2018" the query becomes:
WHERE e.date_of_use NOT IN ('11-11-2018, 11-12-2018')
whereas the right format would be:
WHERE e.date_of_use NOT IN ('2018-11-11', '2018-11-12')
i.e. each date should be intoduced separately inside IN and the date format is YYYY-MM-DD.
To handle also the case where events do not exists for a venue:
SELECT * FROM venues v
JOIN reservations r ON v.venue_id = r.venue_id
LEFT JOIN events e ON e.reservation_id = r.reservation_id
AND (e.date_of_use IS NULL OR e.date_of_use NOT IN ('2018-11-11', '2018-11-12'))

Answer 3

You can structure your array in php like this:
<?php
$DateArray=array();
$DateArray=["11-11-2018", "12-11-2018","11-11-2018", "11-12-2018"];
$Dates='(';
foreach ($DateArray as $key => $value)
{ $Dates=$Dates." ".$value.","; }
$Dates=rtrim($Dates,",");
$Dates=$Dates.")"; // contains ( 11-11-2018, 12-11-2018, 11-11-2018, 11-12-2018)
?>
And append the php variable like this:
SELECT * FROM venues v, reservations r, events e
WHERE v.venue_id = r.venue_id
AND e.reservation_id = r.reservation_id AND e.date_of_use NOT IN .$Dates;

Answer 4

Why don't use simplfy your query for debug?
Something like
SELECT * FROM events e
WHERE e.date_of_use NOT IN ('11-11-2018', '11-12-2018')
Replace dates array using implode function in PHP.
Also you would better use date type rather than text.
https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format