public function addConnection($name, $dsn, $username = null, $password = null, $options = [])
    {
        //default driver options
        static $defaultOptions = array(
            \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
            //PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        );
        if (isset($options['prefix'])) {
            $prefix = $options['prefix'];
            unset($options['prefix']);
        } else {
            $prefix = '';
        }
        $this->configs[$name] = [
            'dsn' => $dsn,
            'username' => $username,
            'password' => $password,
            'prefix' => $prefix,
            'options' => $options + $defaultOptions,
        ];

        return $this;
    }