protected function nullifyEmptyNullables($table)
    {
        $columns = scheme()->columns($table);

        foreach ($this->data as $key => &$value) {
            if (!array_key_exists($key, $columns)) {
                continue;
            }

            if (!$columns[$key]->getNotnull() && empty($value)) {
                $value = null;
            }
        }
    }