Deleting from a table does not remove row - php

Question

DISCLAIMER: I am aware of SQL Injection, I am getting the function done first.
My delete from button does not seem to remove my row in my SQL table
products-one-time.php
This is the output of my foreach, the numbers below the delete button are the groupids, just to show they are unique.
this is the code for the delete button, it redirects to clinics_buttons.vc.php on click.
<a href="clinics_buttons.vc.php<?php echo '?delete-coupongroup='.$rowCouponGroup['groupid']; ?>" onclick="return confirm('Delete this group?');">
<button class="btn btn-danger btn-sm full_width" data-toggle="modal">
<i class="fa fa-edit"></i>DELETE
</button>
</a>
<?php echo $rowCouponGroup['groupid']; ?>
clinics_buttons.vc.php
<?php
session_start();
$routePath = "../";
require_once($routePath . "_config/db.php");
$dbConfig = new config_db();
$db = $dbConfig->init();
$delete_coupongroup = $_GET['delete-coupongroup'];
if (isset($_GET['delete-coupongroup'])) {
$stmt = $db->prepare("DELETE FROM `product_onetime` WHERE groupid = $delete_coupongroup");
$stmt->execute();
header('Location: ' . $_SERVER['HTTP_REFERER']);
}
?>
this is the product_onetime table
What I see is that my code seems to look like they are connected, but the delete button does not work. I tried to manually do the SQL in phpmyadmin, for example:
DELETE FROM `product_onetime` WHERE groupid = 5
Doing it manually works, but the php/sql does not. Would like some input.

Answer 1

My guess is that the file clinics_buttons.vc.php is not executed at all, because the code we see in the question is inside a <form>. In this case, the button behavior overrides the link behavior and the browser will submit the form instead of following the link.
You should be able to see that in the network tab of your development tools in your browser.
As a quick fix, change the button from a submit button into a push button:
<button type="button" class="btn btn-danger btn-sm full_width" data-toggle="modal">
<i class="fa fa-edit"></i>DELETE
</button>
A better solution would be not to use a button at all. Just make the link look like a button by using CSS styling. Or alternatively, remove the code from outside the outer form tag and give it its own form using clinics_buttons.vc.php as the form action.