Re: About Entity Relation Diagram
Date: Fri, 31 Dec 2004 12:49:18 GMT
Message-ID: <iVbBd.4307$JC2.3756_at_newsread2.news.atl.earthlink.net>
"Silver" <argytzak_at_med.auth.gr> wrote in message
news:cps5ij$e9u$1_at_nic.grnet.gr...
> Thanks you for the reply.
>
> I thought that normalizing was all about making flat tables into tables
with
> as less columns as possible.
>
No. Normalization is about storing one fact in one place.
If many facts are stored in one place, access will be difficult. If one fact is stored in many places, update will be difficult. This is an oversimplification. But it's better than what you were working with.
IMO, you would be well advised to postpone questions of normalization until later on in the design process, when you do your logical design.
About all you want to get out of the ER model is a set of well thought out attributes. These will result in a set of well designed columns when you go to logical design. Then, you can ask questions about whether all the columns in a given table belong in that table.
It's not a question of "100 is too many". A table can suffer from normalization problems with only three columns in it, if they are the wrong columns.
And normalization is not the holy grail of database design. Received on Fri Dec 31 2004 - 13:49:18 CET