From: Richard Huxton <dev@archonet.com>
To: sad <sad@bankir.ru>
Cc: Rosser Schwarz <rosser.schwarz@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: feature request ?
Date: Fri, 25 Jun 2004 10:21:52 +0100
Message-ID: <40DBEEB0.40203@archonet.com> (raw)
In-Reply-To: <200406251154.05331.sad@bankir.ru>
References: <200406250816.47781.sad@bankir.ru>
<200406251020.41387.sad@bankir.ru>
<40DBE35A.70104@archonet.com>
<200406251154.05331.sad@bankir.ru>
sad wrote:
>>sad wrote:
>>
>>>On Friday 25 June 2004 09:37, Rosser Schwarz wrote:
>>>
>>>>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.
>>>
>>>READ THE THREAD BEFORE ANSWER
>>
>>WHAT MAKES YOU THINK HE HASN'T?
>
>
> I had answered to the proposal to PROHIBIT NULL VALUES
Umm - what proposal?
Geoffrey 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).
You replied:
> really ?
> what about (13 < NULL)::BOOL
Which is an example where a boolean variable is undefined/not set/null.
In reply to you, Rosser Schwarz wrote:
> 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.
None of which suggests prohibiting nulls.
>
>>The key point of argument, and where the problem is with your (13 <
>>NULL)::BOOL point is this:
>
>
> IT IS NOT MY PROBLEM !!! it is an EXAMPLE WHY WE CAN NOT PROHIBIT NULLS !!!
Umm - who is suggesting prohibiting nulls? I've re-read the entire
thread and can't find any such suggestion. Is this one of those
occasions where the different dialects of English are causing confusion?
--
Richard Huxton
Archonet Ltd
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, sad@bankir.ru, rosser.schwarz@gmail.com
Subject: Re: feature request ?
In-Reply-To: <40DBEEB0.40203@archonet.com>
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