Re: Does entity integrity imply entity identity?
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 04 Aug 2009 20:04:34 -0300
Message-ID: <4a78be8a$0$23771$9a566e8b_at_news.aliant.net>
>
> I have trouble understanding the 13 rules as anything very profound or
> significant. They are nothing like a set of necessary and sufficient
> definitions and to me are more like informal observations on some properties
> of a relational system. Rule 12 seems especially odd. As far as I understand
> it at all, Rule 12 is basically a rule that says you can't break any of the
> other rules!
>
> We have much better science of the relational model today than in 1985 so it
> does puzzle me why people still cite Codd's Rules as if they feel they are
> still important.
Date: Tue, 04 Aug 2009 20:04:34 -0300
Message-ID: <4a78be8a$0$23771$9a566e8b_at_news.aliant.net>
David Portas wrote:
> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
> news:4a7884c6$0$23751$9a566e8b_at_news.aliant.net...
>
>>Rule 3 is absolutely iffy. I tend to consider Rule 4 solid. Some might >>question the necessity of Rule 4, and I know I have some serious >>reservations about the catalog design Codd proposed in RM/V2, but it seems >>perverse to me to deprive those who need to manage data the best tools to >>manage the data about the managed data.
>
> I have trouble understanding the 13 rules as anything very profound or
> significant. They are nothing like a set of necessary and sufficient
> definitions and to me are more like informal observations on some properties
> of a relational system. Rule 12 seems especially odd. As far as I understand
> it at all, Rule 12 is basically a rule that says you can't break any of the
> other rules!
>
> We have much better science of the relational model today than in 1985 so it
> does puzzle me why people still cite Codd's Rules as if they feel they are
> still important.
Codd was an important man as far as relational database management goes. It's important because people are still being taught stuff that Codd wrote--the good right along with the not quite as good.
How will folks who are new to the topic learn which is which if we do not discuss the topic? Received on Wed Aug 05 2009 - 01:04:34 CEST