Re: circular relationships ok?
Date: Thu, 02 Mar 2006 09:21:45 +0100
Volker Hetzer schrieb:
> Just in general, are circular relationships something that
> can always be avoided?
> Or, given a model with a circular relationship, possibly
> spanning several tables, is there a way to get rid of them?
One approach consists in using the concept-oriented data model as follows.
2. After that any relationship you define in this acyclic graph of
tables will use only subtables. In other words, if table A has a
relationship with table B then there is a common subtable C which is
used to establish it (there can be more subtables for complex
relationships). For example, a relationship between a customer and its
products can be implemented via common Order table:
This model avoids the problem of cycles in a principled manner. It provides also many other advantages and conveniences. Instead of modeling relationships via an arbitrary graph we use a concrete structure of ordered tables for that. Querying, grouping/aggregation, inference are also made easier in such an approach.
http://conceptoriented.com Received on Thu Mar 02 2006 - 09:21:45 CET