Authenticate.php

<?php
session_start();
$DB_HOST = 'localhost';
$DB_USER = 'cyberwol';
$DB_PASS = 'm74c3tg^vxmpH8t7aVj9';
$DB_NAME = 'phplogin';
$con = mysqli_connect($DB_HOST, $DB_USER, $DB_PASS, $DB_NAME);
if ( mysqli_connect_errno() ) {
    die ('Failed to connect to MySQL: ' . mysqli_connect_error());
}
if ( !isset($_POST['username'], $_POST['password']) ) {
    die ('Username and/or password does not exist!');
}
if ($stmt = $con->prepare('SELECT id, password FROM accounts WHERE username = ?')) {
    $stmt->bind_param('s', $_POST['username']);
    $stmt->execute();
    $stmt->store_result();
    if ($stmt->num_rows > 0) {
        $stmt->bind_result($id, $password);
        $stmt->fetch();
        if ($_POST['password']==$password) {
            $_SESSION['loggedin'] = TRUE;
            $_SESSION['name'] = $_POST['username'];
            $_SESSION['id'] = $id;
            echo 'Welcome ' . $_SESSION['name'] . '!';
            header('Location: https://x-sim.co.uk/home.php');
        } else {
            header('Location: https://x-sim.co.uk/loginfailed.html');
        }
    } else {
        header('Location: https://x-sim.co.uk/loginfailed.html');
    }
    $stmt->close();
} else {
    echo 'Could not prepare statement!';
}
?>