Re: Conceptual, Logical, and Physical views of data

From: David Cressey <>
Date: Sun, 11 Sep 2005 18:15:47 GMT
Message-ID: <nv_Ue.10322$>

"dawn" <> wrote in message

> I know and I apologize for not yet understanding. This pointer issue
> seems one of the big motivators for relational theory, so I want to
> "get it". I understand why this was problematic when related to memory
> locations, but I don't understand the big downside of using logical
> pointers, reference values, foreign keys -- what's the difference?


I have learned, over time, to be cautious when you say there's something you "don't understand."

When I first "met" you in this news group, you were talking about something important that you didn't understand, from reading and rereading Codd's 1970 paper. I think it was about normalization.

Somewhat foolishly, I trucked on down to the library and reread the Codd paper, which I had not looked at for over a decade. I then proceeded to explain to you what I thought I understood it to be saying.

In the subsequent exchanges between you and me, you gave me to understand that you knew everything that I knew about relational theory and practice, and then some. You had simply reached the opposite from mine as to the merits of the relational data model.

I do not feel the need to repeat that exercise.

In my long career, I have taught relational database programming and design to literally hundreds of customers and employees of DEC. I've even taught this material in Spanish about three times. In the course of that experience, I've had to explain why a foreign key is not the same thing as a pointer about a half a dozen times.

But I have little, if anything, to teach to you. I need not teach you anything that you already know to be true. I cannot teach you anything that you already know to be false. What's left? Received on Sun Sep 11 2005 - 20:15:47 CEST

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