Fixed #20501 -- failure of datetime queries with timezones under Oracle

        # 'second' instead -- cx_Oracle chops the fraction-of-second part

        # off of datetime objects, leaving almost an entire second out of

        # the year under the default implementation.

        first = '%s-01-01'

        second = '%s-12-31 23:59:59.999999'

        return [first % value, second % value]

        bounds = super(DatabaseOperations, self).year_lookup_bounds_for_datetime_field(value)

        if settings.USE_TZ:

            bounds = [b.astimezone(timezone.utc).replace(tzinfo=None) for b in bounds]

        return [b.isoformat(b' ') for b in bounds]

    def combine_expression(self, connector, sub_expressions):

        "Oracle requires special cases for %% and & operators in query expressions"