RE: Counterquestion - is Oracle a He or a She - or an It or
- From: "Mercadante, Thomas F (LABOR)" <Thomas.Mercadante@xxxxxxxxxxxxxxxxx>
- To: <ldutra@xxxxxxxxxxxxx>, <jim_kennedy@xxxxxxxxxx>
- Date: Mon, 8 Aug 2005 11:36:34 -0400
Leandro,
I don't believe Nulls are ambiguous at all. Maybe to you they are, but not to
me.
They mean nothing. They are the great void. They cannot be interpreted to
mean anything else. Quite simple really.
It is up to the application to properly deal with them. A properly designed
application may force the user to fill in a column. Or maybe for a specific
column, a null is appropriate because it does not matter.
For example, in the case of the allergy question. It might be appropriate to
force the Doctor to select at least one response. Maybe "No Known Allergies"
or "Did not Reply" is the appropriate response. This is why we have a NOT NULL
constraint. To force something to be entered.
But in the case of the question "Have you ever been pregnant?" For a male,
this would be appropriate to be null. It might be appropriate for a female
also if she did not want to answer the question.
So it's all a matter of using the tools that are given to us.
Tom
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Leandro Guimaraes Faria C. Dutra
Sent: Monday, August 08, 2005 11:21 AM
To: jim_kennedy@xxxxxxxxxx
Cc: Niall Litchfield; oracle-l@xxxxxxxxxxxxx; oracle-l-bounce@xxxxxxxxxxxxx;
psinger1@xxxxxxxxxxxxx
Subject: RE: Counterquestion - is Oracle a He or a She - or an It or a
hermaphrodite
oracle-l-bounce@xxxxxxxxxxxxx gravou em 2005-08-08 12:20:02:
> So your DB is context-dependent. NULLs attack.
NULLs are ambiguous, their interpretation depend on context. If
SQL allowed us to define special values, we'd have a better solution, as
currently exist in Tutorial D (only implemented in a toy DBMS, Rel) and D4
(Alphora Dataphor).
--
Leandro Guimarães Faria Corcete DUTRA
Administrador de Bases de Dados +55 (11) 4390 5383
Toyota do Brasil Ltda ldutra@xxxxxxxxxxxxx
São Bernardo do Campo, SP BRASIL
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