def get_columns(self, with_aliases=False):
        """
        Return the list of columns to use in the select statement. If no
        columns have been specified, returns all columns relating to fields in
        the model.

        If 'with_aliases' is true, any column names that are duplicated
        (without the table names) are given unique aliases. This is needed in
        some cases to avoid ambiguitity with nested queries.

        This routine is overridden from Query to handle customized selection of
        geometry columns.
        """
        qn = self.quote_name_unless_alias
        qn2 = self.connection.ops.quote_name
        result = ['(%s) AS %s' % (self.get_extra_select_format(alias) % col[0], qn2(alias))
                  for alias, col in self.extra_select.iteritems()]
        aliases = set(self.extra_select.keys())
        if with_aliases:
            col_aliases = aliases.copy()
        else:
            col_aliases = set()
        if self.select:
            only_load = self.deferred_to_columns()
            # This loop customized for GeoQuery.
            for col, field in izip(self.select, self.select_fields):
                if isinstance(col, (list, tuple)):
                    alias, column = col
                    table = self.alias_map[alias][TABLE_NAME]
                    if table in only_load and col not in only_load[table]:
                        continue
                    r = self.get_field_select(field, alias, column)
                    if with_aliases:
                        if col[1] in col_aliases:
                            c_alias = 'Col%d' % len(col_aliases)
                            result.append('%s AS %s' % (r, c_alias))
                            aliases.add(c_alias)
                            col_aliases.add(c_alias)
                        else:
                            result.append('%s AS %s' % (r, qn2(col[1])))
                            aliases.add(r)
                            col_aliases.add(col[1])
                    else:
                        result.append(r)
                        aliases.add(r)
                        col_aliases.add(col[1])
                else:
                    result.append(col.as_sql(quote_func=qn))

                    if hasattr(col, 'alias'):
                        aliases.add(col.alias)
                        col_aliases.add(col.alias)

        elif self.default_cols:
            cols, new_aliases = self.get_default_columns(with_aliases,
                    col_aliases)
            result.extend(cols)
            aliases.update(new_aliases)

        result.extend([
                '%s%s' % (
                    self.get_extra_select_format(alias) % aggregate.as_sql(quote_func=qn),
                    alias is not None and ' AS %s' % alias or ''
                    )
                for alias, aggregate in self.aggregate_select.items()
        ])

        # This loop customized for GeoQuery.
        for (table, col), field in izip(self.related_select_cols, self.related_select_fields):
            r = self.get_field_select(field, table, col)
            if with_aliases and col in col_aliases:
                c_alias = 'Col%d' % len(col_aliases)
                result.append('%s AS %s' % (r, c_alias))
                aliases.add(c_alias)
                col_aliases.add(c_alias)
            else:
                result.append(r)
                aliases.add(r)
                col_aliases.add(col)

        self._select_aliases = aliases
        return result
dataset/ETHPy150Open CollabQ/CollabQ/vendor/django/contrib/gis/db/models/sql/query.py/GeoQuery.get_columns/original