Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cimshop!davidm From: cimshop!davidm@uunet.UU.NET (David S. Masterson) Newsgroups: comp.databases Subject: Re: Integrity Constraints (in OODBs) Message-ID: Date: 21 Mar 91 22:03:50 GMT References: <669391394.14558@minster.york.ac.uk> Sender: davidm@cimshop.UUCP Distribution: comp Organization: Consilium Inc., Mountain View, California Lines: 28 In-reply-to: itana@minster.york.ac.uk's message of 19 Mar 91 14:03:15 GMT >>>>> On 19 Mar 91 14:03:15 GMT, itana@minster.york.ac.uk said: Itana> Does anyone know if it is possible to specify integrity Itana> constraints in ONTOS? Itana> I would also be grateful if someone could suggest good Itana> references on how integrity has been treated in Object Itana> Oriented Databases. That reminds me that I wanted to ask a question about how constraints are supported in OODBs. If I understand the precepts of object-orientation (and I could be way off), objects support constraints as a behaviour in their definition. While doing their processing, they check that a behavioral constraint is not violated by their processing. However, this seems to be related to the definition of the object itself whereas constraints may be based on the definition of the relationships of multiple objects. For instance, a constraint on object A might be that it cannot exist unless object B also exists (referential integrity). If an attempt to delete object B is made, though, what in the definition of the behaviour of B would prevent the operation until corresponding As have been deleted? Must both objects A and B be modified to account for the referential integrity constraint? -- ==================================================================== David Masterson Consilium, Inc. (415) 691-6311 640 Clyde Ct. uunet!cimshop!davidm Mtn. View, CA 94043 ==================================================================== "If someone thinks they know what I said, then I didn't say it!"