Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!pt.cs.cmu.edu!sei!dmc
From: dmc@sei.cmu.edu (Dawn Cappelli)
Newsgroups: comp.databases
Subject: Re: Do you normalize?
Keywords: normalization
Message-ID: <3665@fp.sei.cmu.edu>
Date: 19 Jul 89 20:44:32 GMT
References: <242@6sigma.UUCP>
Reply-To: dmc@sei.cmu.edu (Dawn Cappelli)
Organization: Software Eng. Inst.;Carnegie-Mellon U.; Pittsburgh, PA 15213   _USA_
Lines: 29


When I first learned to design a relational database (6 years ago) I was 
taught to create an entity-relationship diagram, then create the tables 
from the final diagram, then normalize those tables.  I've found that to be
an effective method, although as I became more experienced a lot of the
stringent steps became second nature and intuitively obvious.  

At this point I still use entity-relationship diagrams.  I find they are
quite valuable as a communication tool between the database developers
and the end-users of the database.  An e-r diagram provides a roadmap of
the database.  As they say, a picture is worth a thousand words!  I have
used them to design a database for end-users who have absolutely no 
concept of what a database is, yet they understood the e-r diagram quite
easily.

After the e-r diagram is completed, I then design the tables.  As I design
the tables, I no longer consciously normalize the data, however, 
normalization is an intuitive process at this point for me.  In addition,
I sometimes make a conscious decision to denormalize tables in order to 
enhance performance.

So, in summary, I think anyone learning to design a database should use
normalization, although it becomes more intuitive and less disciplined as
experience develops.  

-- 
Dawn Cappelli	dmc@sei.cmu.edu   sei!dmc     (412) 268-6170

This is only my opinion, and doesn't necessarily reflect the opinion of the SEI.