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
toanything (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.
NULLis the *unknown* value; it's impossible to meaningfully> compare it to anything else. Try (NULL = NULL)::boolean.
It'sNULL,> 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
