public static function getConnection(
        $id,
        $provider = null,
        $host = null,
        $user = null,
        $name = null,
        $password = null,
        $settings = null
    ) {
        if (isset(self::$conn[self::$id = $id])) {
            return self::$conn[$id];
        }

        return self::$conn[$id] = new self(
            $provider,
            $host,
            $user,
            $name,
            $password,
            $settings
        );
    }