Re: In an RDBMS, what does "Data" mean?

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:X4jDc.100639$Hg2.58756_at_attbi_s04...
> "mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message
news:40dd54f7$0$48920$e4fe514c_at_news.xs4all.nl...
> > >
> > > Yes. But if the *same* *data* is stored in both, then M can (normally)
> > > express more. (ie if order is not stored as data, then M can still
> > > express it.)
>
> Can you give an example of something that M can express that
> R cannot, if each is given an informationally-equivalent dataset?
>
> Note that leaving some info out of the R view would not qualify.

I've heard claims that M can capture more information than R, but I see no evidence of that. It is more the case that M DOES capture more information than R. An analyst does their thing, an implementation follows, and M has captured more of the problem domain.

An obvious difference is that the analyst doesn't choose to restrict cardinality to 1 all over the place in M as is common in R. Additionally, one piece of data that is captured in M as a by-product of the work done by the analyst is that the list of files in the system is pretty close to the list of entities in the minds of the users. The tables in R are a superset of that with no standard means of identifying these entities to the end-users, although you could come up with a set of views (that need to be tuned and split out into many more in order to make them efficient etc).

--dawn Received on Wed Jun 30 2004 - 01:40:33 CEST