Re: Why are empty VARCHAR2S always NULL?

From: Tom Hoffmann <trh411_at_earthlink.net>
Date: Wed, 21 Aug 2002 23:06:41 GMT
Message-ID: <52V89.1876$HJ1.120283@newsread1.prod.itd.earthlink.net>

On Wed, 21 Aug 2002 12:12:27 -0400, Niall Litchfield wrote:

> "Wolfram Roesler" <wr_at_grp.de> wrote in message
> news:Xns9271AB88C729Awrgrpde_at_62.153.159.134...

>> "Niall Litchfield" <n-litchfield_at_audit-commission.gov.uk> wrote in
>> news:3d639ab8$0$8507$ed9e5944_at_reading.news.pipex.net:
>>
>> > Maybe I'm just sheltered but I can't see any reason why anyone would
>> > regard using the absence of any entry as signifying NULL a bug. What
>> > representation would you use for unknown.
>>
>> NULL is unknown, but '' is a known empty string. At least that's what
>> I'd expect it to be.

> I see that the rest of your comments follow from this. I don't see you
> answering my second question though. If not an empty string what
> representation would you use for NULL in a character field.

The Perl programming language uses "undefined" to describe any variable that has not been explicitly given a value, and provides the mechanism to check whether or not a variable is defined/undefined.

The minute one says a variable (or column in the context of this discussion) is NULL, it seems to me that its value is not unknown, but is in fact NULL, which is an explicit denotation of its value. Received on Wed Aug 21 2002 - 18:06:41 CDT