My PHP code is not working for deleting record in mysqli database

I am trying to delete a displayed record using delete button but it is not deleting the record in mysqli database. Here is the code:

require_once('db_connect.php');
if(isset($_GET['del']))
{
$delete_id=$_GET['del'];
 $delete_query = "DELETE FROM table_name WHERE id='$delete_id'";
 $run=mysqli_query($mysqli,$delete_query);
 if($run){
    $output = "User has been deleted";
 }
 else{
    $output = "Error deleting record";
 }
}

and here is the button link code

<td><a href='?del=<?php echo $id ?>'><button class='btn btn-danger'>Delete this Record</button></a></td>

after deleting i get the right message that 'user has been deleted ' but the record in database exists and actually not deleted.
Please have a look and suggest a correction.
Thanks in advance.