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Home -> Community -> Usenet -> comp.databases.theory -> Key attributes with list values was Re: What are the differences ...KEY

Key attributes with list values was Re: What are the differences ...KEY

From: dawn <dawnwolthuis_at_gmail.com>
Date: 25 Feb 2006 08:53:28 -0800
Message-ID: <1140886408.778878.179090@i39g2000cwa.googlegroups.com>


Marshall Spight wrote:
<snip>
> I ask because I am working on software for working with relations.
> Early designs had special purpose support for keys, foreign keys,
> etc., but in later revisions this has been dropped in favor of a
> more general constraint engine. But one still needs to require
> a minimum of one key, and I think some amount of special
> key-related code is useful; one could automatically suggest
> normalizations, for example. This would be facilitated by
> having a canonical form for keys.

Since I know you favor including lists, are you planning to permit candidate keys to have list values? My logical data modeling experience (but no further research) suggests that multivalued keys are not desirable. This is one of the reasons to possibly identify a candidate key as the primary key and restrict it to a single (although possibly composite) value. I'm stepping out of my comfort zone to state this, however, as I have no knowledge about implementation details. I don't know if this comment is relevant or helpful, but will send in case it is. Cheers! --dawn Received on Sat Feb 25 2006 - 10:53:28 CST

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