Let's say I have acquisitions at regular intervals and each acquisition I get different measures.
Each meausre has a value and a numeric type id (1 = temperature, 2 = humidity ecc...) I want user to insert text description for type id he knows, if he wants. I end up having this 3 tables: measures = Table('measure', metadata, Column('id', Integer, primary_key=True), Column('acq_id', Integer, ForeignKey('acquisitions.id'), nullable=False) Column('type_id', Integer, ForeignKey('types.id'), nullable=False), Column('value', Float, nullable=False), ) acquisitions = Table('acquisitions', metadata, Column('id', Integer, primary_key=True), Column('datetime', DateTime, nullable=False), ) types = Table('types', metadata, Column('id', Integer, primary_key=True, autoincrement=False), Column('desc', String, nullable=False), ) [class definitions...] orm.mapper(Acquisition, acquisitions) orm.mapper(Type, types) orm.mapper(Measures, measure, properties={ 'type': orm.relationship(Type, backref='measures'), 'acquisition': orm.relationship(Acquisition, backref='measures'), }) Now, while I want, deleting an acquisition, all child measures are deleted too, I DON'T want any modification in data if the user edit types, for example: - deletes a type (related measures are not deleted and their type_id is not changed in null value) - edits the type.id (precedent associated measures are not updated to new type_id but mantain the old one). How can I achieve this? I guess I should use cascade in relationship but can't figure how Thanks for your support! -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.