Hello stackoverflow people. I need help with my script. I've got registration file and index file, when I made case for index file, that when action is register, load registration.php header,(index.php?action=register) my registration script does not work! I get error that variable mysql not found(in register.inc.php file). But when URL is normal - www.website.com/register.php then everything is OK, do you guys know what kind of problem is this? How can I fix it?
Here is my register.in.php file start:
<?php
include_once 'db_connect.php';
include_once 'psl-config.php';
$error_msg = "";
if (isset($_POST['username'], $_POST['email'], $_POST['p'])) {
    // Sanitize and validate the data passed in
    $username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
    $email = filter_input(INPUT_POST, 'email', FILTER_SANITIZE_EMAIL);
    $email = filter_var($email, FILTER_VALIDATE_EMAIL);
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        // Not a valid email
        $error_msg .= '<p class="error">The email address you entered is not valid</p>';
    }
    $password = filter_input(INPUT_POST, 'p', FILTER_SANITIZE_STRING);
    if (strlen($password) != 128) {
        // The hashed pwd should be 128 characters long.
        // If it's not, something really odd has happened
        $error_msg .= '<p class="error">Invalid password configuration.</p>';
    }
    $prep_stmt = "SELECT id FROM members WHERE email = ? LIMIT 1";
    $stmt = $mysqli->prepare($prep_stmt);
Error is in the last row where $mysqli. That $mysql is from file do_connect.php:
<?php
include_once 'psl-config.php';
$mysqli = new mysqli(HOST, USER, PASSWORD, DATABASE);
Help please?
 
    