Re: Proposal: 6NF

"Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message news:R8iVg.1104$cz.15593_at_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.

How? Not every view is updatable. Also, updatable views can violate the assignment principle. Received on Fri Oct 06 2006 - 11:39:23 CEST