Delete SQL data from database with php page - php

Question

I am making an application to secure doors and windows in your house. The app is done for 80% but i can't figure out how I can delete a database record of a door of house. The problem is I can't find a way to read out the right data to delete the record. Could you please look in my scripts i made for the delete page?
I have one page to insert al the data in a table to overview all the devices that are "connected" to the app.
<section>
<form action="verwijderen.php" method="post">
<?php
$sql = "SELECT device_id, naam, plaats.plaats, type.type, status FROM devices, type, plaats, status
WHERE devices.type_id = type.type_id
AND plaats.plaats_id = devices.plaats_id
AND status.status_id = devices.status_id";
$result = $con->query($sql);
if ($result->num_rows > 0)
{
echo '<table><tr><td>ID</td><td>Naam</td><td>Plaats</td><td>Type</td><td>Status</td><td>Verwijderen</td></tr>';
while($row = $result->fetch_assoc())
{
echo '<tr>';
echo '<td>' .$row['device_id']. '</td>';
echo '<td>' .$row['naam']. '</td>';
echo '<td>' .$row['plaats']. '</td>';
echo '<td>' .$row['type']. '</td>';
echo '<td>' .$row['status']. '</td>';
echo '<td>';
?>
<input type="submit" value="Verwijderen" name="submit">
</form>
<?php '</td>';
}
echo '</table>';
}
?>
</section>
The other page I have is the page to delete the records that are inserted into the table. The problem with the deleting is I can't find a way to delete the records. Adding the records to the database in html with a $_POST/$_GET works fine..
<?php
error_reporting(E_ERROR);
include '../dbconnect.php';
//$connection = mysql_connect("", "", ""); // Establishing Connection with Server
//$db = mysql_select_db("cerar", $connection); // Selecting Database from Server
if(isset($_POST['submit']))
{ // Fetching variables of the form which travels in URL
}
mysqli_close($con); // Closing Connection with Server
//header( "refresh:3;url=index.php" );
?>

Answer 1

Create a form for each row of your table, and include a hidden input field containing the key value to pass to the server. So move the opening form tag just before the input type="submit" you have, and include another hidden input, like this:
<form action="verwijderen.php" method="post">
<input type="hidden" value="<?=$row['device_id']?>" name="device_id">
<input type="submit" value="Verwijderen" name="submit">
</form>
Then in PHP you can find the device id that must be deleted in $_POST['device_id']. It should be easy to write the delete statement.

Answer 2

<section>
<form action="verwijderen.php" method="post">
<?php
$sql = "SELECT device_id, naam, plaats.plaats, type.type, status FROM devices, type, plaats, status WHERE devices.type_id = type.type_id AND plaats.plaats_id = devices.plaats_id AND status.status_id = devices.status_id";
$result = $con->query($sql);
if ($result->num_rows > 0) {
echo '<table>
<thead>
<tr>
<th>ID</th>
<th>Naam</th>
<th>Plaats</th>
<th>Type</th>
<th>Status</th>
<th>Verwijderen</th>
</tr>
</thead>
<tbody>';
while($row = $result->fetch_assoc()){
echo '<tr>';
echo '<td>' .$row['device_id']. '</td>';
echo '<td>' .$row['naam']. '</td>';
echo '<td>' .$row['plaats']. '</td>';
echo '<td>' .$row['type']. '</td>';
echo '<td>' .$row['status']. '</td>';
echo '<td>';?>
<input type="hidden" value="<?php echo $row['device_id']; ?>" name="device_id">
<input type="submit" value="Verwijderen" name="submit">
<?php '</td>';
}
echo '</tbody>
</table>';
}
?>
</form>
</section>
PHP Code
<?php
error_reporting(E_ERROR);
include '../dbconnect.php';
extract($_POST);
//$connection = mysql_connect("", "", ""); // Establishing Connection with Server
//$db = mysql_select_db("cerar", $connection); // Selecting Database from Server
if(isset($_POST['submit']) && $_POST['submit'] == 'Verwijderen')
{
//delete query
//DELETE FROM devices WHERE device_id = $device_id
}
mysqli_close($con); // Closing Connection with Server
//header( "refresh:3;url=index.php" );
?>