def select_as_dataframe(self, table_name, columns=None, where=None, extra=None):
        """
        Get data in the database and return fetched data as a
        :py:class:`pandas.Dataframe` instance.

        :param str table_name: |arg_select_table_name|
        :param list columns: |arg_select_as_xx_columns|
        :param str where: |arg_select_where|
        :param str extra: |arg_select_extra|
        :return: Table data as a :py:class:`pandas.Dataframe` instance.
        :rtype: pandas.DataFrame
        :raises simplesqlite.NullDatabaseConnectionError:
            |raises_check_connection|
        :raises simplesqlite.TableNotFoundError:
            |raises_verify_table_existence|
        :raises simplesqlite.OperationalError: |raises_operational_error|

        :Example:
            :ref:`example-select-as-dataframe`

        .. note::
            ``pandas`` package required to execute this method.
        """

        import pandas

        if columns is None:
            columns = self.fetch_attr_names(table_name)

        result = self.select(
            select=AttrList(columns), table_name=table_name, where=where, extra=extra
        )

        if result is None:
            return pandas.DataFrame()

        return pandas.DataFrame(result.fetchall(), columns=columns)
Get data in the database and return fetched data as a
        :py:class:`pandas.Dataframe` instance.

        :param str table_name: |arg_select_table_name|
        :param list columns: |arg_select_as_xx_columns|
        :param str where: |arg_select_where|
        :param str extra: |arg_select_extra|
        :return: Table data as a :py:class:`pandas.Dataframe` instance.
        :rtype: pandas.DataFrame
        :raises simplesqlite.NullDatabaseConnectionError:
            |raises_check_connection|
        :raises simplesqlite.TableNotFoundError:
            |raises_verify_table_existence|
        :raises simplesqlite.OperationalError: |raises_operational_error|

        :Example:
            :ref:`example-select-as-dataframe`

        .. note::
            ``pandas`` package required to execute this method.