Re: Data Display & Modeling
Date: Sat, 8 May 2004 08:50:58 -0500
Message-ID: <c7ioke$n22$1_at_news.netins.net>
"Eric Kaun" <ekaun_at_yahoo.com> wrote in message
news:YzQmc.86$Qm5.68_at_newssvr32.news.prodigy.com...
> And I should add that Levene contributed to the "Nested Relational Data
> Model", which I believe Date discusses in Intro-DB Systems as unnecessary,
> and proceeds to show why the basic relational model can tackle the same
> problem domains without modification (and with additional benefits). I
can't
> remember the details - Dawn?
Although Date talks about relation-valued attributes in Intro-DB, I haven't found anything describing a nested relational model (but I've not read all the way through). Instead he adds in the GROUP and UNGROUP operators in D. However, there are a couple of papers that you can pay for and download from dbdebunk.com where Date discusses nested structures and asks questions about MultiValue (PICK) systems and then by Pascal who gives reasons not to use relational-valued attributes even though they are not outside of the scope of relational theory (anymore).
> Not evidence of anything, except perhaps willingness to invent novelties
> rather than exploiting what's already available
Of course, that is what Codd did.
> and solid.
mathematically solid or history-of-savingcompanies-big-bucks-solid?
> also the case with much of the industry - not only do fads get jumped on,
> but they acquire momentum quickly as the "oldies" are forgotten...
Yes, and if you find an oldie that still gets played and sung, then it is likely a good one. smiles --dawn Received on Sat May 08 2004 - 15:50:58 CEST