Re: So what's null then if it's not nothing?

<michael_at_preece.net> wrote in message news:1132718136.236806.36710_at_f14g2000cwb.googlegroups.com...
>
> mountain man wrote:
>
>> "paul c" <toledobythesea_at_oohay.ac> wrote in message
>> news:OhPgf.573740$1i.24270_at_pd7tw2no...
>> > Frank Hamersley wrote:
>> >> JOG wrote:
>> >>
>> >>> michael_at_preece.net wrote:
>> >>>
>> >>>> "A value of the Boolean data type is either true or false. The truth
>> >>>> value of unknown is sometimes represented by the null value."
>> >>>>
>> >>>> Dodgy or what?! It would be better to use a large cumbersome robot
>> >>>> waving its arms about saying "does not compute" than to use null for
>> >>>> this.
>> >>>>
>> >>>> Mike.
>> >>>
>> >>>
>> >>> I for one _really_ hope some database corporate representatives are
>> >>> reading this thread, and take this feature into consideration for
>> >>> their
>> >>> future releases.
>> >>
>> >>
>> >> Errr...pardon me for being dense...but exactly what is the "feature"
>> >> we
>> >> so desperately need?
>> >>
>> >> Cheers, Frank.
>> >
>> > I was trying to exercise restraint, but I guess I've gotten sucked in
>> > along with some smart people. puts me in good company, i suppose ...
>> >
>> > i don't understand why such a question ends up with so much space on
>> > the
>> > "databases.theory" newsgroup. is it because there is no such group as
>> > "comp.databases.practice.etc"?
>>
>>
>> Its because the theory side of databases is lead at the moment
>> by a large hand waving robot called "The Pedagogy of the RM".
>> This practice (as most human concerns go) is self perpetuating
>> and has been at it in excess of 30 years.
>>
>> The problem is that evolution in the world external to the academic
>> vision of the relational model has not been matched by evolution
>> of the model, or evolution of its interfaces to other valid models
>> and ideas in the (information technology) environment.
>>
>> Technically, the NULL can mean a different thing to every DBMS
>> and its treatment (if any) will vary between vendors. Tabulate the
>> vendors of all RDBMS and DBMS software and you will see
>> that this is a fact.
>
> Would it be inappropriate to describe this state of affairs as
> "ridiculous"?

It is life, it is history, it is what has happened since 1979. It is reality, it is technological reality of what is happening this very day today across the planet.

I would not call it rediculous. It is the way things are. Things are the way they are for a whole ecology of reasons, and their history tracks their evolution.

What is rediculous about the way a certain tract of natural bushland grows back again after a bushfire?

It may appear rediculous to those who may wish to associate themselves with a specific perspective on the overall process of the last 35 years, but on the other hand, there are obviously thousands of various perspectives on this "state of affairs", some of them commercially inspired, etc, etc, etc.

We deal with RDBMS vendor software. It is diverse in its treatment of nulls, but there are emergent standards.

RM theorists such as Codd and Date espouse different methodologies for the consistent handling of nulls.

So what? This is the way of the world. It is all just opinion in the end, so make peace with that fact, and conserve energy for the evaluation of such opinions.

In practice, one does not have the luxury of infinite reflection and one must select an appropriate opinion, run with it in a consistent fashion, and be aware of how it responds to change management.

Good luck.

>> Some people believe that unknown and unknowable values
>> cannot exist, and they might be happy to contemplate nulless
>> existence in a vendor software that represents their notion
>> of reality.
>>
>> Others believe that it is better to allow for the possibility of
>> unknown and unknowable values, and select and/or write
>> their RDBMS software accordingly.
>>
>>
>> None of this is against the law (yet), so
>> opinion is thus diverse.
>>
>>
>>
>>
>>
>>
>>
>>
>> --
>> Pete Brown
>> IT Managers & Engineers
>> Falls Creek, Australia
>> www.mountainman.com.au/software
>
Received on Wed Nov 23 2005 - 09:19:28 CET