Re: What does this NULL mean?
Date: 14 Dec 2005 07:05:07 -0800
Message-ID: <1134572707.151136.207630_at_f14g2000cwb.googlegroups.com>
mountain man wrote:
> "David Cressey" <dcressey_at_verizon.net> wrote in message
> news:K2Qnf.2517$0z.2002_at_trndny02...
> >
> > "mountain man" <hobbit_at_southern_seaweed.com.op> wrote in message
> > news:ttrnf.19034$ea6.17392_at_news-server.bigpond.net.au...
> >
> >> Dependent upon the measure of complexity of your database
> >> it may be argued that the design is never complete because it
> >> is under constant evolution.
> >
> > [snip]
> >
> > Your post is outstanding, perhaps the best I've read in this thread.
> >
> > I think "change management in databases" deserves a discussion of its own.
>
>
> There has been limited discussion here, and there are articles
> about on this issue under the keyphrase of "schema evolution".
>
> The issue is avoided by Date et al (AFAIK) whereas it is
> precisely this issue of schema change that should be subject
> to the principles espoused by the relational model.
>
> The RM guides the design of new databases, and it obviously
> also must guide the evolution of old databases, but this aspect
> has not yet been thrashed out in any formalised manner.