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From: zuker@6sigma.UUCP (Hunter Zuker)
Newsgroups: comp.databases
Subject: Re: ER versus dependency normalization methods.
Message-ID: <361@6sigma.UUCP>
Date: 12 Dec 90 17:07:15 GMT
References: <34324@netnews.upenn.edu> <1990Dec11.003251.4494@inel.gov> <2370@edat.UUCP>
Organization: Six Sigma CASE, Inc.
Lines: 52

Brian Douglass) writes:

>I'm starting a new project . . .

>In this life I am now looking at CASE tools to automate the whole 
>analysis and design process.  In particular I have been interested in
>the teamwork series by Ingres/Cadre and IDE's software through
>pictures.  

It's funny you should ask ;-)   As some of you know we have a data 
normalization product called the Canonizer (because it uses the 
canonical sythesis approach to normalization).  A bridge between CADRE's
Teamwork Entity Relationship Diagrams (ERDs) and our product has already been 
built, because the ERDs don't take you to third normal form.  And we 
are just completing a bridge to IDE's Software Through Pictures ERDs for 
the same reason.

>Since these products claim not only to assist in the diagramming
>of systems, but also the creation of database schemas and relationships,
>how useful has anyone found them to be?  I mean going from user 
>interviews to actual data models was always a hair puller at best,
>but now may be a moot point, the tool does it all for you (scarry!).
>Some tools will not only generate all of your schemas, but even your
>4gl code!

Well, they generate your schemas, but the schemas have tables that
are just copies of the entities and don't necessarily have anything to
with higher levels of normalization (3NF, 4NF, or BCNF).

I can't comment on the generation of 4GL, but real work and decisions
have to happen someplace.

>So how about it.  Are CASE tools going to relieve us all the need
>to decide between ER and DN, and do it all for us?  Sort of like
>microwave brownies.  Pour in the interviews, mix all around,
>nuke for 3 minutes and presto, instant system!

Obviously I don't think ERDs are going to do it.  There is too much
ambiguity.  You can generate 3NF ERDs, but just because you have an
ERD doesn't mean you'll get any higher level of normalization than
first normal form.

Though we have found that our product is real useful to go from interview,
to model, to normalized schema, it is still an iterative process.  There
is real work to be done to identify and find the correct relationships
between data.  

Hunter 

-- 
Hunter Zuker		Six Sigma CASE, Inc.	 13456 SE 27, Suite 210
zuker@6sigma.UUCP       (206) 643-6911           Bellevue, WA 98005-4211