Re: BUG #1921: NULL<>NULL ?!?!?!?!?!?!?

On Thu, Sep 29, 2005 at 09:38:54AM +0100, BogDan Vatra wrote:
>
> The following bug has been logged online:
>
> Bug reference: 1921
> Logged by: BogDan Vatra
> Email address: bog_dan_ro(at)yahoo(dot)com
> PostgreSQL version: 8.0.3
> Operating system: win xp pro
> Description: NULL<>NULL ?!?!?!?!?!?!?
> Details:
>
> Please execute this query:
>
> create table test (id serial, tt varchar(50));
> insert into test (tt) values(NULL);
> select tt from test where tt=NULL;
>
> This should return 1 row but ...
> An then try
>
> select tt from test where tt<>NULL;
>
> 0 row(s) !!!

It is not a bug. NULL isn't a datum. It's a state of ignorance. If
I don't know what your birthday is and I don't know what your
coworker's birthday is, I also don't know whether they are equal, and
so the only right answer to "Is BogDan's birthday unequal to his
coworker's?" is "I don't know."

HTH :)

Cheers,
D
--
David Fetter david(at)fetter(dot)org http://fetter.org/
phone: +1 510 893 6100 mobile: +1 415 235 3778

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