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From:Paul DuBois Date:October 27 2001 3:11pm
Subject:Re: Problem with query
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At 9:38 -0400 10/27/01, jim barchuk wrote:
>Hi Carl!
>>  Paul DuBois writes:
>>  > NULL basically means "unknown value", so saying WHERE x = NULL cannot
>>  > work, even if x is NULL.  That means "where one unknown value = another
>>  > unknown value", which cannot be evaluated with any certainty. :-)
>>  It is sort of odd, though, that x = NULL returns something which
>>  appears to be undefined rather than something well-defined
>>  (such as false all the time) or an error (which could be said to
>>  be well-defined, if errors are considered to be valid responses
>>  to queries...).
>Well which would you prefer, false or error? Dealing with errors is
>annoying if not necessary. 'False' is incorrect -if- the field is allowed
>to contain 'nothing' because NULL means it does contain nothing.

I think what Carl meant was that it was strange that the WHERE x = NULL
query returned a non-empty result set.  I noticed that in the original
message, too.  I don't know what accounts for it.

>ob-filter-words: database table sql
>jim barchuk
Problem with queryBrendin26 Oct
  • RE: Problem with queryRavi Raman26 Oct
    • RE: Problem with queryBrendin26 Oct
      • RE: Problem with queryPaul DuBois26 Oct
        • Re: Problem with queryCarl Troein27 Oct
          • Re: Problem with queryjim barchuk27 Oct
            • Re: Problem with queryPaul DuBois27 Oct
              • Re: Problem with queryjim barchuk27 Oct
RE: Problem with queryAndrew Murphy29 Oct