what data models cant do
Date: Sat, 14 May 2005 15:33:08 GMT
Message-ID: <USohe.2729$E7.1492_at_news-server.bigpond.net.au>
"Kenneth Downs" <knode.wants.this_at_see.sigblock> wrote elsewhere:
> IMHO the unified theory describes data organized into tables but which
> contains system-managed columns and tables. Because all business rules
> resolve to database specifications, we are not so much seeking a model
> that
> allows management of human-created code, but rather a model that fully
> supports the generation of automated values. The normal toy example is an
> automated column extended = price * qty, but if you systematize that and
> add some other nifty stuff, you can create a database that can do anything
> that procedural code can do, and organize the entire process flawlessly
> from analysis to real-world use.
I have been looking around for an article in which I had seen a similar
treatment of "derivations" since you posted the above, and this evening
found it again. You may already have seen this one:
What data models cant do --- David Hay
In summary, the article details at least four categories of things not adequately described in data models:
- implied assumptions
- when optional relationships are activated
- how to keep multiple paths between entities
- derivations [derived data --- see above]
Pete Brown
Falls Creek
Oz
www.mountainman.com.au
Received on Sat May 14 2005 - 17:33:08 CEST