Deleting record from database with button in PHP - php

Question

I have to delete a record from database using a button but my delete query does not work. Records are entered in database successfully with insertion query. I followed exact tutorial for php code available on YouTube "How to delete records from database with PHP & MySQL" by "kanpurwebD". The code in tutorial works fine but my code still does not delete record. (I have 2 records entered in database).
My code is as follows:
<div class="container">
<div class="row">
<form action='add_record.php' method='get'><button type='submit' name='id' value='submit' class='btn btn-default'>ADD RECORD</button><br />
</form>
<table class="table table-hover table-responsive">
<thead>
<tr>
<th>Topic #</th>
<th>Name</th>
<th>Admin ID</th>
<th>Edit</th>
<th>Delete</th>
</tr>
</thead>
<tbody>
<?php
echo '<br />';
$query = "SELECT * FROM tb_topic";
$result = $con->query($query);
if(isset($_POST['submitDeleteBtn'])){
$key = $_POST['keyToDelete'];
$check = "Select * from tb_topic where topic_id = '$key'";
if(mysqli_num_rows($con, $check)>0){
$query_delete = mysqli_query($con,"Delete from tb_topic where topic_id = '$key'");
echo 'record deleted';
}
}
while($query_row = mysqli_fetch_array($result)) {?>
<tr>
<td><?php echo $query_row['topic_id'];?></td>
<td><?php echo $query_row['topic_name'];?></td>
<td><?php echo $query_row['aid'];?></td>
<td><input type = 'checkbox' name = 'keyToDelete' value = "<?php echo $query_row['topic_id'];?>" required></td>
<td><input type="submit" name="submitDeleteBtn" class="btn btn-danger"></td>
</tr>
<?php }
?>
</html>

Answer 1

I got it resolved by using following statement:
if(isset($_GET['delete'])) {
$page = filter_input(INPUT_GET, 'delete', FILTER_VALIDATE_INT, FILTER_NULL_ON_FAILURE);
$sql = "DELETE FROM tb_topic WHERE topic_id = $page";
}
$_GET() was not taking id as int so I tried typecasting it and it worked for me.