process.php

<?php include 'database.php'; ?>
<?php session_start(); ?>

<?php
    //Check to see if score is set
    if (!isset($_SESSION['score'])) {
        $_SESSION['score'] = 0;
    }

    //Check if Post ist submited
if ($_POST) {
    $number = $_POST['number'];
    $selected_choice = $_POST['choice'];
    $next = $number + 1;

    /*
     * Get total questions
     */
    $query = "SELECT * FROM questions";
    // Get result
    $results = $mysqli->query($query) or die($mysqli->error . __LINE__);
    $total = $results->num_rows;

    /*
     * Get correct choice
     */
    $query = "SELECT * FROM choices
                WHERE question_number = $number AND is_correct = 1";

    //Get result
    $result = $mysqli->query($query) or die($mysqli->error . __LINE__);

    //Get row
    $row = $result->fetch_assoc();

    //Set the correct choice
    $correct_choice = $row['id'];

    //Compare
    if ($correct_choice == $selected_choice) {
        //Answer is correct
        $_SESSION['score']++;
    }

    //Check if the last question ?
    if ($number == $total) {
        header("Location: final.php");
        exit();
    } else {
        header("Location: question.php?n=".$next);
    }
}
?>