Re: Normalization and DBMS

"Leandro Guimarães Faria Corsetti Dutra" <leandro_at_dutra.fastmail.fm> wrote in message news:pan.2004.05.12.03.46.00.535494_at_dutra.fastmail.fm...
> Em Tue, 11 May 2004 22:40:10 -0500, Dawn M. Wolthuis escreveu:
>
> > "Leandro Guimarães Faria Corsetti Dutra" <leandro_at_dutra.fastmail.fm>
> > wrote in message
news:pan.2004.05.12.03.22.43.667655_at_dutra.fastmail.fm...
> >> Em Tue, 11 May 2004 20:10:10 -0500, Dawn M. Wolthuis escreveu:
> >>
> >> > it seems to have a direct correlation to the flexibility of a system
> >> > to withstand years of requirements changes
> >>
> >> Quite to the contrary. With nested tables, the only way to ever reach
> >> the subtable is thru the supertable.
> >
> > What problems are caused by this? I suspect there are some, but then
> > there are tradeoffs.
>
> See how you want to have it both ways. You want to 'withstand
> [...] requirement changes', but also a less powerful, more complex,
> less flexible structure.

Could you point me to any experiments that would yield such a conclusion of graphs being "less powerful, more complex, less flexible structure"?

> > One thing that works well is the integrity -- when
> > the parent goes away, so does the child table and there is no chance
that
> > a child will be born without a parent.
>
> This is trivial. Even SQL does it right.

Not if is isn't specified. --dawn Received on Wed May 12 2004 - 16:08:37 CEST