def distinct_sql(self, fields):
        if fields:
            raise NotImplementedError('DISTINCT ON fields is not supported by this database backend')
        else:
            return 'DISTINCT'
Returns an SQL DISTINCT clause which removes duplicate rows from the
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Django-1.6.10/django/db/backends/__init__.py/BaseDatabaseOperations.distinct_sql