Re: feature request ?

From: Richard Huxton <dev(at)archonet(dot)com>
To: sad <sad(at)bankir(dot)ru>
Cc: Rosser Schwarz <rosser(dot)schwarz(at)gmail(dot)com>, pgsql-sql(at)postgresql(dot)org
Subject: Re: feature request ?
Date: 2004-06-25 09:21:52
Message-ID: 40DBEEB0.40203@archonet.com
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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(at)bankir(dot)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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