Re: Views for denomalizing

"Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message news:8lnk01hpeuj5g94hkl8bm6bvdfk66perdk_at_4ax.com...
> On Sat, 5 Feb 2005 18:24:22 -0600, "Dawn M. Wolthuis"
> <dwolt_at_tincat-group.comREMOVE> wrote:
>
>>> I don't see a lot of usefulness in creating such a term.
>>
>>Does the other topic I started on this on how products that now describe
>>one
>>of their features as being that they are Non-First-Normal-Form (NF2 or
>>NFNF,
>>for example) are now, be definition, potentially IN 1NF by the new
>>definition.
>
> As far as I know such products are very far from being relational so
> it does not make sense to talk about normalization in that context.

I didn't think they were relational either until I read Codd's 1970 paper and saw that his use of the term really was tied directly to an actual mathematical definition of relation. If one were to match a data model to the products (and I will grant that such was not discussed in the early 60's when these were designed), mathematical relations would be very appropriate as they, in fact, employ mathematical functions, a subset of relations (only relations with a primary key). And many of the normal forms are quite appropriate for this model, just not what was once called 1NF.

>>That is great, but hiding that fact by simply redefining underlying terms
>>is
>>confusing the message. People can now say some of the same words and mean
>>something entirely different and their audience might not even know.
>
> But when a term is not well defined it is a good thing to define it
> properly.

I agree, which is why I try to keep us on track with the mathematical definition of relation, which is very well defined and quite agreed upon within the mathematical community as best I can tell.

> We always can explain what 1NF really means to the confused
> audience.

I didn't understand that statement, so you I guess I'm one of the "confused", eh?

>>>>This always throws me off since it is SQL NULLS -- three-valued logic
>>>>NULLs -- that are disallowed. For any tools where NULL is a value,
>>>>rather
>>>>than the absense of value, this is not an issue.
>>>
>>> I don't know such tools. SQL nulls are not values.
>>
>>Perhaps you will trust me that there are such tools where "null" is the
>>name
>>of a value which can be compared using a two-valued logic.
>
> Ok, but I suppose that those tools are very far from being relational,
> so they are irrelevant to the discussion of 1NF.

No, again, modeling is done with mathematical functions, a subset of all relations, but the same subset that many relational theorists zero in on for best practices or even in their def of relation sometimes (IIRC)

>>> But there is a rule that says that all the tuple attributes must have
>>> a value, so nothing with nulls might be a relation.
>>
>>Correction: Nothing with a SQL null or a three-valued logic null can be a
>>relation, but for tools where "null" is a value, this is not an issue.
>
> But I am afraid that such tools don't use relations.

I guess that each time you say that, I'll correct you. I do know where you are coming from with that statement, as I had thought these were not relational myself, but they are as relational as any other product where the data can be modeled as relations. They lack other features and add in other features not present in most RDBMS's, but those are not part of the definition of "relational" in its original and mathematically correct form.

>>> IBM knows very little about the Relational Model. You should ignore
>>> all that.
>>
>>Wasn't Codd an IBM employee when he wrote his early papers?
>
> Yes but it does not change anything. IBM never understood the RM and
> they created the SQL aberration. Codd, Date and now Darwen abandoned
> IBM.
When did Darwen leave IBM? I'm not in the inner circle and am apparently not keeping current on such matters (perhaps the news didn't make People magazine?). Nevertheless, I'm sure there are some at IBM who would spout the same doctrine as you.

>>I'm thinking
>>there are people at IBM who know quite a bit about relational theory,
>>whether they opt to completely buy into it or not.
>
> If you know a bit about relational theory you always opt to buy into
> it.

Oh really? I know a bit about relational theory. I once bought into it. I've learned a bit more. I'm not as gullible now.

> If still there are people at IBM who know about relational theory it
> is clear that they don't have any decision power.

Or perhaps they know about it, but the wealth of experience from employees and customers of IBM might have lead them to some other conclusions. smiles. --dawn

> Regards
>
Received on Thu Feb 10 2005 - 03:20:18 CET