Re: Proposal: 6NF

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 06 Oct 2006 01:17:37 GMT
Message-ID: <R8iVg.1104$cz.15593@ursa-nb00s0.nbnet.nb.ca>

Sampo Syreeni wrote:

> On 2006-10-05, Bob Badour wrote:
>

>> So, you are saying that laying zero eggs includes the inapplicability 
>> of the whole concept of laying anything. If zero suffices, why NULL?

>
> Because a bird that has laid zero eggs might then be observed to lay
> more, and we would want to assign a nonzero value to its eggs_laid. With
> camels it's different.

Are you now suggesting you want to use NULL to indicate that a bird laid an egg? That seems absurd.

>>> Furthermore, at the time your code is expected to be finalized, you 
>>> only know that there will be animals, some of which lay eggs, but you 
>>> don't know which kinds of properties all of the animals eventually 
>>> described in the database might have.
>>
>>
>> Ah, but one will have to know what those are before one commits the 
>> schema and one will have to know the properties of interest before one 
>> writes a query.

>
>
> The whole point of my exercise was that judicious use of nulls allows
> you to escape the first half, at least in this one case.

Bullshit.

  In my opinion
> such separation of concerns is a worthy design goal,

What concerns? The concerns for laziness and stupidity? Null certainly has no use either for the concern for correctness or for the concern for performance.

  because schemas
> tend not to be entirely static and added dependent attributes are
> perhaps the most common form of real life schema evolution.

I suggest updatable views handle schema evolution while NULL contributes nothing useful. Received on Thu Oct 05 2006 - 20:17:37 CDT