How to delete row with PDO and with restriction - php

Question

I have two tables in mysql database, the first one is 'kavomati' where are coffee machines and second table is 'lokacije' where are locations of those coffee machines and that tables have relations with primary key in database and it is set ON DELETE RESTRICT so I can't delete some location which have coffee machine and that's good. I created one page where I see all locations and there I have modal button for add new location, modal buttons for edit each location and at the end of each address I added delete modal button for each row. What I want to do is to delete every location which has no coffee machine but first I must make a query in php and check is certain location have any coffee machine. I'm newbie in php so I would appreciate any help.
This is my code to display locations of my database table and modal buttons:
<?php
if(!isset($_SESSION['user_id'])){
header('Location: ../../index.php');
}
try{
$stmt = $conn->prepare('SELECT id,ulica,kc_broj,mjesto FROM lokacije ORDER BY id ASC');
$stmt->execute();
$data = $stmt->fetchAll(PDO::FETCH_ASSOC);
}
catch(PDOException $e){
if(DEBUG === true){
header('Location:error/db_error.php?err_msg='.$e->getMessage());
}
else{
header('Location:error/db_error.php?err_msg');
}
}
?>
<div class="panel-heading clearfix">
<h3 style="float:left; margin:0;">Lokacije</h3>
Dodaj lokaciju
</div>
<table class="table table-hover">
<tr>
<th>ID</th>
<th>Ulica</th>
<th>Kućni broj</th>
<th>Mjesto</th>
<th></th>
</tr>
<?php
foreach($data as $value){
?>
<tr>
<td>
<?php echo $value['id'].'.'?>
</td>
<td>
<?php echo $value['ulica']?>
</td>
<td>
<?php echo $value['kc_broj']?>
</td>
<td>
<?php echo $value['mjesto']?>
</td>
<td align="right">
<a href="#" data-toggle="modal" data-target="#edit_loc<?php echo $value['id']?>" role="button" class="btn btn-success btn-sm edit">
<i class="fa fa-pencil-square-o"></i> Uredi
</a>
<div class="modal fade edit-u" id="edit_loc<?php echo $value['id']?>" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
<div class="modal-dialog" role="document">
<div class="modal-content" style="text-align:left;">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="myModalLabel">Uredi lokaciju broj <?php echo $value['id']?></h4>
</div>
<form action="" method="POST">
<div class="modal-body">
<input type="hidden" name="id_lokacije" id="id_lokacije" value="<?php echo $value['id']?>">
<div class="form-group ulica">
<label for="ulica">Ulica</label>
<input type="text" class="form-control" name="ulica" id="ulica-u" placeholder="Ostavite prazno polje ako ne želite mjenjati naziv kavomata" value="">
</div>
<div class="form-group kc_broj">
<label for="kc_broj">Kućni broj</label>
<input type="text" class="form-control" name="kc_broj" id="kc_broj-u" placeholder="Ostavite prazno polje ako ne želite mjenjati naziv kavomata" value="">
</div>
<div class="form-group mjesto">
<label for="mjesto">Mjesto</label>
<input type="text" class="form-control" name="mjesto" id="mjesto-u" placeholder="Ostavite prazno polje ako ne želite mjenjati naziv kavomata" value="">
</div>
</div>
</form>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Zatvori</button>
<button type="button" class="btn btn-primary" id="edit_loc">Spremi</button>
</div>
</div>
</div>
</div>
<a href="#" data-toggle="modal" data-target="#delete_loc<?php echo $value['id']?>" role="button" class="btn btn-danger btn-sm">
<i class="fa fa-trash-o"></i> Izbriši
</a>
<div class="modal fade" id="delete_loc<?php echo $value['id']?>" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content" style="text-align:center;">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">×</span><span class="sr-only">Close</span></button>
<h2 class="modal-title" id="myModalLabel" style="color:#a80b27;text-transform:uppercase;font-size:1.6rem;">upozorenje !</h2>
</div>
<div class="modal-body">
<h5>Da li si siguran da želiš obrisati lokaciju broj <b><?php echo $value['id']?></b>?</h5>
</div>
<div class="modal-footer">
<a href="include/locations/delete.php?id=<?php echo $value['id']?>" role="button" class="btn btn-danger">
Da, siguran sam!
</a>
<button type="button" class="btn btn-default" data-dismiss="modal">Ne</button>
</div>
</div>
</div>
</div>
</td>
</tr>
<?php
}
?>
</table>
<div class="modal fade" id="add_locModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="myModalLabel">Dodaj novu lokaciju</h4>
</div>
<form action="" method="POST">
<div class="modal-body">
<div class="form-group ulica">
<label for="ulica">Ulica</label>
<input type="text" class="form-control" name="ulica" id="ulica" placeholder="Ulica">
</div>
<div class="form-group kc_broj">
<label for="kc_broj">Kućni broj</label>
<input type="text" class="form-control" name="kc_broj" id="kc_broj" placeholder="Kućni broj">
</div>
<div class="form-group mjesto">
<label for="mjesto">Mjesto</label>
<input type="text" class="form-control" name="mjesto" id="mjesto" placeholder="Mjesto">
</div>
</div>
</form>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Zatvori</button>
<button type="button" class="btn btn-primary" id="add_loc">Dodaj</button>
</div>
</div>
</div>
And this is my delete.php script:
require '../../config/init.php';
require '../services/xss.php';
if(isset($_SESSION['user_id']) && isset($_GET['id'])){
$id = $_GET['id'];
try{
$stmt = $conn->prepare('DELETE FROM lokacije WHERE id=:id NOT IN(SELECT k.id FROM kavomati k WHERE k.id=lokacije.id)');
$stmt->bindParam(':id',$id);
$stmt->execute();
header('Location:../../coffee-locations.php');
}
catch(PDOException $e){
if(DEBUG === true){
header('Location:../../error/db_error.php?err_msg='.$e->getMessage());
}
else{
header('Location:../../error/db_error.php?err_msg');
}
}
}
else{
header('Location:../../index.php');
}
?>
I tried something like this but it doesn't work.Please help.

Answer 1

It shouldn't work as well since your query syntax is total wrong. It should be
DELETE FROM lokacije
WHERE id NOT IN(SELECT id FROM kavomati)