try {

    $db = mysqli_connect(db_hostname, db_user, db_password, db_base);

    if (!$db) {
        echo "Error: Unable to connect to MySQLi." . PHP_EOL;
        echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
        echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;
        exit;
    } else {

        define("db_dsn", $db );

    }


} catch (Exception $e) {

    echo 'Caught exception: ',  $e->getMessage(), "\n";

}