Re: Views for denomalizing

"Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message news:jmu6011qbjoejhumkrlakd5nhscsvfe213_at_4ax.com...
> On Thu, 3 Feb 2005 23:18:29 -0500, "Alan" <not.me_at_rcn.com> wrote:
>
>>Normalization occurs at a logical level (note I did not say "the" logical
>>level
>
> Why not?
>
>>, as I am just distinguishing logical from physical, not getting into
>>logical vs conceptual- IOW, let's say logical and conceptual are the same
>>thing
>
> But they are very different.
>
>>Views are a physical construction
>
> Very very wrong!
>
> Views are as logical as the rest of the relation variables.
>
> It seems that you are calling physical model to the logical model and
> logical model to the conceptual model. This is a very common confusion
> in the literature.
>
> This also explains your confusion between the conceptual and logical
> levels.
>
>> and have nothing to do
>>with normalization.
>
> I disagree. View values are relations like any other relation. We can
> check whether a view is in a given normal form, but it does not mean
> that we should normalize the views.
>
>>attributes
>>[apply FDs to get to the next level, revealing PKs in the process]:
>>relations (entities and relationships - an ERD is often created here)
>>[apply transformation rules* to the ERD to get to the next level]
>>-----boundry between logical and physical----------
>
> An ERD is a conceptual design, and if you apply "transformation rules"
> to the ERD what you get is an incomplete logical design.
>
>> Remember, a view is
>>nothing but a stored SQL statement
>
> A view is defined using a query statement, but a view is a relation or
> table variable.

I hope it is not too disturbing to you, Alfredo, that I am in 100% agreement with you and also seem to use the same language as you on these matters. Maybe that just means I'm learning. smiles. --dawn Received on Fri Feb 04 2005 - 17:12:28 CET