Using AJAX to execute a php file - php

Question

I've created a custom template for wordpress and I'm trying to execute some php code (deleteUser.php) to delete a record from a db but I'm not sure how to run the code without using alert. At the moment I'm just getting an empty dialog box rather than my php code deleting a row from the db.
ajax part
<?php
echo '<script>';
echo 'function dltUser(siteID){';
echo "jQuery.ajax({";
echo "data: 'siteID=' + siteID,";
echo "url:"."'".get_stylesheet_directory_uri()."/deleteUser.php"."',";
echo "method: 'POST', ";
echo "success: function(msg) {";
echo "alert(msg);";
echo "}";
echo "});";
echo '}';
echo '</script>';
?>
deleteUser.php - the code to delete a row
<?php
include_once($_SERVER['DOCUMENT_ROOT'].'/wp-config.php' );
global $wpdb;
$siteID = $_POST['siteID'];
echo '$wpdb->query("DELETE FROM my_site WHERE SiteID = %d",$siteID)';
?>

Answer 1

Don't wrap the $wpdb->query(...) inside an echo, that won't execute the query, it will just output the command as a string, and you want to return a value to the AJAX function after the code is executed, not echo it.
If you don't want to use alert() to prevent the message from displaying to the user, use console.log() instead, see Console.log()
Also, as Rory said, don't use an echo for every single line you write. Either use . to concatenate or write plain HTML and inject the PHP variables where needed.
Resuming, your code should look something like this:
Ajax:
<script>
function dltUser(siteID) {
$.ajax({
data : siteID,
url : <?php get_stylesheet_directory_uri(); ?> + '/deleteUser.php',
method : 'POST',
success : function(msg) {
console.log(msg);
}
})
}
</script>
deleteUser.php
<?php
include_once ($_SERVER['DOCUMENT_ROOT'] . '/wp-config.php');
global $wpdb;
$siteID = $_POST['siteID'];
if ($wpdb->query("DELETE FROM my_site WHERE SiteID = %d", $siteID)) {
return 'Success';
}
return 'Error';
?>

Answer 2

Remove the alert. An empty dialog box means alert is being called, but you have no message. However the PHP script ran returning an HTTP response with a 200 OK code. If you don't want the popup, remove the alert. If you want a message, echo something at the end of your script.
Oh, and ditch the closing ?> if there isn't any output after it.