So in this case you need to add an extra post value to your jQuery ajax call. The key would be action and the value playlist_data_delete.

check_ajax_referer(‘something’);
check_ajax_referer(‘something’, ‘wpsec’);
check_ajax_referer(‘wpsec’, ‘something’);
check_ajax_referer(‘wpsec’);

all response 0

Now, only one slight thing,

 id: id, wpsec: '<?php wp_create_nonce('something'); ?>' }

doesn’t return anything in wpsec:, so I made a function instead and echoed that, which works.

But I still get response 0 :/

As you, I can’t see where we should get 0. Here’s the code:

add_action ('wp_footer', 'delete_mpl_jquery');
function delete_mpl_jquery() { 

$noncense = wp_create_nonce('something'); ?>

<script type="text/javascript">
jQuery(document).ready(function($){
	$('.box a').click(function() {
	id = $(this).parents('div.box').attr('id');
		id = id.replace(/delete-mpl-/, "");
		el = $(this);
	jQuery.post('<?php echo admin_url('admin-ajax.php'); ?>', { id: id, wpsec: '<?php echo $noncense; ?>', ajax: 'true' }, function(response) {
		//callback function here
	});
	return false;
});
});

</script>
<?php } ?>

<?php //this is the SQL and php for deleting playlists

add_action('wp_ajax_playlist_data_delete', 'playlist_delete');

function playlist_delete() {
	global $wpdb;
	$wpdb->show_errors();

	$piktud =  $_POST['id'];

	check_ajax_referer('something', 'wpsec');

	$table_name = $wpdb->prefix . "playlist_master";

	if(isset($_POST['ajax'])) {
		if(isset($_POST['id'])) {
  			$id = (int) $_POST['id'];
			if($wpdb->query("DELETE FROM $table_name WHERE id = ".$id)) {
				echo 'excellent';
				exit(1);
			}
		}
	}
die(69);
} ?>

To send across the extra data, in this case the nonce you could do this:

jQuery.('#delete-link').click(function() {
	jQuery.post('<?php echo admin_url('admin-ajax.php'); ?>', { id: '<?php echo $id; ?>', wpsec: <?php wp_create_nonce('your-action-text'); ?>' }, function(response) {
		//callback function here
	});
	return false;
});

Something like that should do the trick. The return false is just there to stop the href from submitting (if you used an href).

Hope that helps & let me know how it goes.

I think a `brewski` is indeed in order. If you noticed the site was down about 5-10 minutes ago I apologise, someone overloaded the server & I had to get onto the admins to get it sorted. All done now though.

I’ve been staring at this all day, I’m sure it’s the solution. Now, I’m just too bug eyed to figure thinks out. Methinks it’s time for a brewski.

Again though as this is function receiving data via AJAX I would add in a nonce & verify it via check_ajax_referer() before even attempting to delete a row so external requests can’t trigger a deletion.

I’ve never made a AJAX call to admin-ajax.php without providing a nonce so maybe it is refusing your AJAX request (returning 0) because no nonce is being verified. Although I’m not sure about that.

Also just another little thing I noticed, you have wrote:

$id = $_POST['id'];
//later in code
  if(isset($_POST['id'])) {

That is slightly backwards, you should probably use:

if(isset($_POST['id'])) {
  $id = (int) $_POST['id'];

Hope that makes sense.

I’ll check a few more things out about why your code could be giving back 0, but let me know if you find anything else in the meantime.