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Home -> Community -> Usenet -> comp.databases.theory -> Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]

Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]

From: VC <boston103_at_hotmail.com>
Date: Fri, 1 Jul 2005 22:02:15 -0400
Message-ID: <5IWdncc2pt00aFjfRVn-tg@comcast.com>


Hi,

[...]
"Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message news:IVhxe.135039$l56.6861917_at_phobos.telenet-ops.be...
> Jon Heggland wrote:
>> Anyway, there is one thing that is bugging me when I read articles about
>> object data models like Calvanese/Lenzerini and Van den Bussche /
>> Paredaens. If objects are just identity points, and the properties of
>> objects are other objects, where do actual data values enter into the
>> picture?
>
> Data values are special objects that have one or more representations
> associated with them by which they are identified.

What's that supposed to mean ? 'Value' is just an element of a domain (data type), like, say, '1' is_a_member_of Integer. Are you proposing a new definition of 'value' ? If so, what is it ? The above is not a formal definition by any stretch of imagination.

>Like LOTs and NOLOTs in NIAM.

I looked briefly at LOT/NOLOT. Did not see much of [formal] defonitions though. Could you please provide a reference or reproduce one ?

[It's not idle curiosity on my part (as was with the 'return' word). I am genuinely interested what the current formalism for the object/network/xml data model is.]

Thanks.

>
> -- Jan Hidders
Received on Fri Jul 01 2005 - 21:02:15 CDT

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