Re: normalization

From: Jared Still <jkstill_at_gmail.com>
Date: Tue, 1 Nov 2005 11:53:07 -0800
Message-ID: <bf46380511011153m28d79a91s4b7ef36b0dcd7ee5@mail.gmail.com>

3rd normal form: attributes must depend ONLY on the the key attribute(s)

Calculated attributes violate that.

To preempt the question "What if the calculated column is calculated from the PK attributes?": if that is the case, then questionable choices were made for the key attributes.

Calculated fields are for reporting. eg. data marts and/or data warehouses.

--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist


On 11/1/05, Chris Stephens <cstephens16_at_gmail.com> wrote:


>

> There is a discussion going on at work concerning calculated fields.

>

> I am claiming that any calculated field in a table is a violation of

> at least 3NF if not 2NF. I can find all sorts of references on the

> web that justify my position but nothing that directly says this

> violates normalization rules.

>

> The person who i disagree with is claiming that 'technically',

> calculated fields do not violate 3NF. They are just not recommended.

> I am unable to find anything on the web coinciding with this argument.

>

> Anyone know of a site with a direct statement that calcualted fields

> violate 2NF/3NF?

>

> thanks,

> chris

> --

> http://www.freelists.org/webpage/oracle-l

>

>

>


--
http://www.freelists.org/webpage/oracle-l

Received on Tue Nov 01 2005 - 13:55:21 CST