Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Codd provided appropriate mathematics ... (was Re: Relational and MV (response to "foundations of relational theory"))

Re: Codd provided appropriate mathematics ... (was Re: Relational and MV (response to "foundations of relational theory"))

From: Eric Kaun <ekaun_at_yahoo.com>
Date: Wed, 03 Mar 2004 13:44:42 GMT
Message-ID: <ejl1c.55384$GT6.254@newssvr33.news.prodigy.com>


"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c1lhip$8lb$1_at_news.netins.net...
> "Eric Kaun" <ekaun_at_yahoo.com> wrote in message
> news:k6r%b.50112$LX2.42031_at_newssvr33.news.prodigy.com...
> > As an aside in this discussion, I've seen "multivalued" defined 2
> different
> > ways in explanations of relational (some of which are really bad).
> >
> > 1. Where attribute A can hold a list of values (type LIST)
> > 2. Where there are attributes A1, A2, A3, A4 (for example), all of the
> same
> > type and meaning. For example, ADDR1, ADDR2, etc.
> > [...]
> > Does 1NF refer to both of these? If not, what's the proper terminology
for
> > each of these cases?
>
> Good question because it is likely clear to most data folks that 1, which
is
> the one more often referred to as multivalued (there is a MultiValue
> trademark associated with one such model) and is not permitted by the
> relational model, is a much better strategy than 2, which is permitted.

Agreed that 2 is awful, but option 3, the relational way, is better yet.

> I don't think there are any theories related to data storage and retrieval
> that would suggest that 2 is good design, but relational data modeling in
> practice is much more likely than others to promote this poor approach

Not really - even in SQL, those who do something like option 2 are vilified and stoned in the town square. People keep doing it, but they're usually uneducated or lazy (since I see it done even with very simple data models where it's completely unnecessary). Received on Wed Mar 03 2004 - 07:44:42 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US