Values in DB speichern

<?php
global $wpdb; 




$list = $_POST['list'];$output = array();$list = parse_str($list, $output);// print_r($output);


$sidebar_implode = implode(',', $output['id']);


echo $sidebar_implode;






$dbname = "xxx";
$servername = "localhost";
$username = "xxx";
$password = "xxx";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);


// Check connectionif ($conn->connect_error) {    die("Connection failed: " . $conn->connect_error);}
echo "Connected successfully";
$sql = "INSERT INTO wptest_woodashboard (id, data)VALUES ('', '$sidebar_implode')";
if ($conn->query($sql) === TRUE) {    
echo "New record created successfully";
} else {    
echo "Error: " . $sql . "<br>" . $conn->error;}
$conn->close();

Query(document).ready(function($) {       
var url = "";       
var raz = 0;
      $( ".order-card" ).sortable({          
cursor: 'move',          
update: function ( event, ui){            //  var predmet = $(this).attr("predmet-id") ;              
var data = $(this).sortable('serialize', { attribute: 'wpdc-sidebar-id' });              
console.log(data);


jQuery.ajax({        
type: "POST",        
url: ajaxurl,         
data: {            
'action': 'my_action_callback',            
'data': jQuery('[data]').val()        
},        
beforeSend: function() {            
alert('before');        
},        
success: function(){          
console.log(data);            
alert('success');
        },        
error: function(){            
alert('error');        
},    
});


...
/*

add_action('wp_ajax_my_action', 'my_action_callback');
function my_action_callback() {  global $wpdb; // this is how you get access to the database




  $name = $_POST['data'];


  $id = '2'; $table_name = $wpdb->prefix . "xxxtest";
  $rows_affected = $wpdb->update( $table_name, array(    'id' => $id,    'data' => $name


  ));






  die(); // this is required to return a proper result}