Re: So what's null then if it's not nothing?

In message <ltdvn1dd5k2cdqthb9s5jjsihpgf9lvsdj_at_4ax.com>, Hugo Kornelis <hugo_at_pe_NO_rFact.in_SPAM_fo> writes
>On Sat, 19 Nov 2005 23:19:58 +0000, Bernard Peek wrote:
>
>>In message <fn5sn19kcr7og6p8hjnodb7j67umo6tbu9_at_4ax.com>, Gene Wirchenko
>><genew_at_ucantrade.com.NOTHERE> writes
>>
>>> Does an object exist? If it does, we get the answer yes. If it
>>>does not, we get the answer no. No NULL is needed.
>>
>>Does my dog exist?
>
>Hi Bernard,
>
>Almost there. Almost.
>
>Does my dig exist? is a yes/no question. The answer to that is a boolean
>value. And booleans are not defined as a data type in SQL. There's a
>reason for that. All SQL data types can also accomodate a Null, but a
>boolean can't. All yes/no questions can allways be answered. Not with
>"yes" (true), "no" (false), or "no answer" (Null), but with "yes", "no",
>or "don't know" (unknown).
>
>A better example would be:
>
>What's the age (in whole years) of my dog?

OK, so what is it's age (in whole numbers)?

-- 
Bernard Peek
London, UK. DBA, Manager, Trainer & Author.