<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _clean_up_columns( self):
 """clean up columns of the NED table .. todo :: - update key arguments values and definitions with defaults - update return values and definitions - update usage examples and text - update docstring text - check sublime snippet exists - clip any useful text to docs mindmap - regenerate the docs and check redendering of this docstring """

        self.log.debug('starting the ``_clean_up_columns`` method')

        tableName = self.dbTableName

        print "cleaning up %(tableName)s columns" % locals()

        sqlQuery = u"""
                set sql_mode="STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
            """ % locals()
        writequery(
            log=self.log,
            sqlQuery=sqlQuery,
            dbConn=self.cataloguesDbConn,
        )

        sqlQuery = u"""
                update %(tableName)s set dist_mod_err = null where dist_mod_err = 0;
                update %(tableName)s set dist_in_ned_flag = null where dist_in_ned_flag = "";
                update %(tableName)s set notes = null where notes = "";
                update %(tableName)s set redshift = null where redshift = 0;
                update %(tableName)s set dist_derived_from_sn = null where dist_derived_from_sn = "";
                update %(tableName)s set hubble_const = null where hubble_const = 0;
                update %(tableName)s set lmc_mod = null where lmc_mod = 0;
                update %(tableName)s set master_row = 0;
                update %(tableName)s set master_row = 1 where primaryId in (select * from (select distinct primaryId from %(tableName)s group by galaxy_index_id) as alias);
            """ % locals()
        writequery(
            log=self.log,
            sqlQuery=sqlQuery,
            dbConn=self.cataloguesDbConn,
        )

        self.log.debug('completed the ``_clean_up_columns`` method')
        return None