Re: Generalised approach to storing address details

"Marshall" <marshall.spight_at_gmail.com> wrote in message news:1166123242.632022.107760_at_16g2000cwy.googlegroups.com...
> On Dec 14, 9:41 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
> > Marshall wrote:
> >
> > > I've never had to program a BOM application, and I've read about them
> > > only a little. I'm not qualified to have an opinion on BOM
> > > specifically.
> > I have programmed BOM applications, and at the time I used a proprietary
> > network model dbms. That experience largely influenced my opinion of the
> > network model.
> >
> > BOM's are not hierarchies, BTW. The general BOM is a DAG.
>
> Interesting.
>
> I've never been exactly clear on what the term "network model"
> means; I've assumed it's quite comparable to an object graph,
> with which I am quite familiar. It is striking to me that a Turing
> complete OO language such as Java can have such a hard
> time with things that a non-Turing complete language such
> as SQL is so good at. And this even for simple, everyday
> tasks like filter-and-sum.

The term "network model" goes back to the 1970s. "Digraph model" might have been somewhat more precise.

It was used to designate databases built along the CODASYL DBTG lines. Records are grouped into sets by pointers to other records, embedded in the records. A record can be a member of more than one set.

The network model and the hierarchical model were generally presented in introductory tutorials about the relational model for purposes of contrast. A few years ago, when I first started reading Dawn's harangues against the relational model in here, she was lamenting that introductory textbooks still present things this way. Dawn, it seems, thinks the contrast presented in the introductory texts is specious, and that the advantages claimed for the relational model are bogus.

I was a little surprised to hear that this contrast is still in textbooks myself, but for different reasons. When the relational model was new, most of the people learning it were familiar DBMSes that were either hierarchical or network. Today, I expect the great majority of people to get their first exposure to the relational model before learning any other kind of DBMS. Hence the tutorial value of the contrast is diminished. Received on Sat Dec 16 2006 - 15:23:52 CET