Re: Normalization and Derived Information
From: Kenneth Downs <firstinit.lastname_at_lastnameplusfam.net>
Date: Thu, 23 Sep 2004 10:29:45 -0400
Message-ID: <pkmuic.rc9.ln_at_mercury.downsfam.net>
> of 1nf,
> 2nf and so forth. <<
>
> Tom Johnston did a series of articles on other forms of redundancy
> than normalization problems that would be worth pulling up.
Date: Thu, 23 Sep 2004 10:29:45 -0400
Message-ID: <pkmuic.rc9.ln_at_mercury.downsfam.net>
--CELKO-- wrote:
>>> I'm wondering about the precise status of derived columns in terms
> of 1nf,
> 2nf and so forth. <<
>
> Tom Johnston did a series of articles on other forms of redundancy
> than normalization problems that would be worth pulling up.
Thanks, will do.
>
> It is bad if you materialize the computed column because it can get
> out of synch with the columns used to compute it. We used to have
> that problem all the time in punch card systems.
A trigger can compute the column and then it is always in sync.
-- Kenneth Downs Use first initial plus last name at last name plus literal "fam.net" to email meReceived on Thu Sep 23 2004 - 16:29:45 CEST