<?php
require_once 'api.php';
$sign = base64_encode( sha1(
$private_key .
base64_decode($_POST['data']) .
$private_key
, 1 ));

$status = $POST_['status'];
$signature = $_POST['signature'];
if($status == 'success') {

echo '<h1>Success</h1>';
    $city = $_POST['city']; // значения, которые вводит пользователь
    $pizza = $_POST['pizza'];
    $adress = $_POST['adress'];
    $code = $_POST['code'];

$dbc = mysqli_connect('host', 'user', 'password', 'database')
or die('Error connecting to MySQL server.');

$query = "INSERT INTO orders (city, pizza, adress, code) " .
"VALUES ('$city', '$pizza', '$adress', '$code')";

$result = mysqli_query($dbc, $query)
or die('Error querying database.');

mysqli_close($dbc);

} else {
echo '<h1>Error</h1>';
}