RE: Counterquestion - is Oracle a He or a She - or an It or a hermaphrodite

oracle-l-bounce_at_freelists.org gravou em 2005-08-05 20:48:41:

> --

        Please don't use the signature separation in the body of the message. Stick to RFC 1855.

> C. It is unknown if you are or are not allergic to anything.
>
> The Dr. should assume C. You have not been asked the question so the
> data in that column is NULL

        Problem is, this is just one of the usual, assumed possible meaning of NULL. NULL should mean nothing, so your interpretation *in this case* is OK; but what we need is a special value to signify UNKOWN. Then we'd define a domain as whatever we want plus the UNKNOWN value; and any other current usages of NULL would each get its own special value. There go interpretation errors, performance problems, conceptual confusion... and NULLs being so ingrained in SQL is on of the various reasons why Date and Darwen propose that a relational language shouldn't try to fix SQL as it's hopeless.

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Leandro Guimarães Faria Corcete DUTRA
Administrador de Bases de Dados      +55 (11) 4390 5383
Toyota do Brasil Ltda              ldutra_at_toyota.com.br
São Bernardo do Campo, SP                        BRASIL


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