Re: Database design, Keys and some other things
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 01 Oct 2005 22:30:56 +0200
Message-ID: <433ef152$0$11068$e4fe514c_at_news.xs4all.nl>
>
> That reminds me of something I read: "the purpose of metaphysics is to
> correct metaphysics", which I think I can justify only by giving a
> longer reply.
>
> I'd say the db only has to be as big as having one more attribute than
> the smallest possible db. Would think this would include most databases.
>
> I'm assuming that by "smallest" we mean a db that only the empty set as
> attribute even though there could be many differently-named relations
> within it.
Date: Sat, 01 Oct 2005 22:30:56 +0200
Message-ID: <433ef152$0$11068$e4fe514c_at_news.xs4all.nl>
paul c wrote:
> mAsterdam wrote:
>> paul c wrote: >>> mAsterdam wrote: >>> >>>> ... When designing a database, we assume a closed world for >>>> the database under design. Aren't you sugessting we >>>> work within that same specific closed world when >>>> designing it? >>> >>> Yes. >>> >>> Also that this makes the notion of "surrogate" meaningless within the >>> CWA. >> >> Well, when you are designing that big a database, >> you are right of course. For all other databases not, though.
>
> That reminds me of something I read: "the purpose of metaphysics is to
> correct metaphysics", which I think I can justify only by giving a
> longer reply.
>
> I'd say the db only has to be as big as having one more attribute than
> the smallest possible db. Would think this would include most databases.
>
> I'm assuming that by "smallest" we mean a db that only the empty set as
> attribute even though there could be many differently-named relations
> within it.
I don't understand. It may be a nice exercise to explain some concepts, but can such a database hold relevant facts for anyone?
The determination of what facttypes will be in the database is defining its closed world (CW). Unless you a designing a database for database design, 'facttypes' will not be in the databases' CW - it will be in the designers CW. Received on Sat Oct 01 2005 - 22:30:56 CEST