def _extract_db_related_names(cls) -> Set:
        """
        Returns only fields that are stored in the own database table, exclude
        related fields that are not stored as foreign keys on given model.
        :return: set of model fields with non fk relation fields excluded
        :rtype: Set
        """
        related_names = cls.extract_related_names()
        related_names = {
            name
            for name in related_names
            if cls.ormar_config.model_fields[name].is_valid_uni_relation()
        }
        return related_names

        Returns only fields that are stored in the own database table, exclude
        related fields that are not stored as foreign keys on given model.
        :return: set of model fields with non fk relation fields excluded
        :rtype: Set
        
ormar/models/mixins/relation_mixin.py