// Check if already installed

if ($step === 1) {

    try {

        $pdo = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASS);

        $stmt = $pdo->query("SHOW TABLES LIKE 'users'");

        if ($stmt->rowCount() > 0) {

            $error = 'Forum is already installed. If you want to reinstall, please drop the database first.';

        }

    } catch (PDOException $e) {

        // Database doesn't exist, which is fine for installation

    }

}