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

vc wrote:

[snip]

> Please read the original article I've referenced for justification and
> the debate beween Codd and Date on the issue of nulls:
> http://www.dbdebunk.com/page/page/1706814.htm.
>

I will say that I was hesitant to take any link to dbdebunk owing to past experience. Some articles I took links to a while back filled me with rage and so I haven't been back. This article was different though - and I thank you for the link.

I find I agree with much of what Date has to say - particularly with his stand on 2VL. I do wish though that I could get them both to see clearly that missing data should be exactly that - missing, nowhere to be found in the database - and that the only valid use for NULL is to represent something that is known to be empty (whether the thing is a set or a scalar). I did, in particular, like the example of the NULL department for an employee who was on leave of absence and would be assigned a role when they got back.

>
> >This is a blunder analogous to saying that the empty string
> > is NULL.
>

Sorry vc - was it Jon that made that point? Can Jon, or perhaps someone else, explain how an empty string differs from a NULL string? I don't want to know about a place-holder for a missing string - I mean a string that is known to be empty.

Mike. Received on Fri Dec 02 2005 - 03:24:15 CET