dadads

<!DOCTYPE html>
<head>
    <html>
<?php
require ('./private/connection.php');
$error = "";
if (isset($_POST['login'])) {
    $error = "";
    $username = $_POST['username'];
    $password = $_POST['password'];
    if ($username == "") {
        $error = "Gebruikersnaam mag niet leeg zijn!";
    } elseif ($password == "") {
        $error = "Wachtwoord mag niet leeg zijn!";
    }
    if ($error == "") {
        try {
            $db = new PDO("mysql:host=".database_host."; dbname=".database_name, database_user, database_password);
            $stmt = $db->prepare("SELECT user_id, user_name, password FROM users WHERE user_name = :username");
            $stmt->execute(array(':username' => $username));
            $data = $stmt->fetch(PDO::FETCH_ASSOC);
            if ($data == false) {
                $error = "Gebruikersnaam en/of wachtwoord klopt niet!";
            } else {
                if (password_verify($password, $data['password'])) {
                    $_SESSION['username'] = $data['username'];
                    $_SESSION['password'] = $data['password'];
                    echo "het klopt!";
                    exit;
                } else {
                    $error = "Gebruikersnaam en/of wachtwoord klopt niet!";
                }
            }
        } catch (PDOException $e) {
            $error = $e->getMessage();
        }
    }
}
?>

    !DOCTYPE html>
    <html>
    <head>
        <meta charset="UTF-8">
        <title>Dashboard: Inloggen</title>
        <link rel="stylesheet" type="text/css" href="../css/panel/style.css">
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/normalize/5.0.0/normalize.min.css">
        <script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
    </head>

<body>
<div class="login">
    <h1>Inloggen</h1>
    <?php if ($error != "") { ?>
        <div class="isa_error"><?php echo $error; ?></div>
    <?php } ?>
    <form action="" method="post">
        <input type="text" name="username" value="<?php if (isset($_POST['username'])) echo $_POST['username'] ?>"
               autocomplete="off"/><br/><br/>
        <input type="password" name="password" value="<?php if (isset($_POST['password'])) echo $_POST['password'] ?>"
               autocomplete="off"/><br><br>
        <button type="submit" name='login' value="Inloggen" class="btn btn-primary btn-block btn-large">Betreed de
            wonderlijke wereld!
        </button>
    </form>
</div>
<script src="../js/index.js"></script>
</body>
</html>