Re: Relational Databases

It's always difficult to give design advice online without the opportunity to research a particular situation in detail. Thorough design generally needs more information than can easily be obtained from a newsgroup dialogue.

Based on your description I would suggest that you make the Router attribute in the Computer table nullable or use some other token to represent the fact that the Router information was not supplied. When the information is needed the default Router value can then be retrieved from the Group table rather than the Computer table.

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David Portas