From: Rosser Schwarz <rosser.schwarz@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: feature request ?
Date: Fri, 25 Jun 2004 00:37:45 -0500
Message-ID: <37d451f70406242237dce4a8e@mail.gmail.com> (raw)
In-Reply-To: <200406250816.47781.sad@bankir.ru>
References: <200406250816.47781.sad@bankir.ru>
On Fri, 25 Jun 2004 08:16:47 +0400, sad <sad@bankir.ru> wrote:
> > Very simply, a boolean may have to values: true or false. It's also
> > possible that it's not been set to anything (NULL).
> really ?
> what about (13 < NULL)::BOOL
Per the semantics of NULL, 13 is neither greater than nor less than
NULL. NULL is the *unknown* value; it's impossible to meaningfully
compare it to anything else. Try (NULL = NULL)::boolean. It's NULL,
also.
Since no value, including NULL, is in any way definitively comparable
to NULL -- the unknown value -- comparing to NULL results in ...
unknown.
Otherwise known as NULL.
/rls
--
:wq
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To: pgsql-sql@postgresql.org
Cc: rosser.schwarz@gmail.com
Subject: Re: feature request ?
In-Reply-To: <37d451f70406242237dce4a8e@mail.gmail.com>
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