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

Jon Heggland wrote:
> In article <1134828509.355442.304890_at_z14g2000cwz.googlegroups.com>,
> boston103_at_hotmail.com says...
> >
> > > So yes, nothing really changes except the notation and the explanations.
> > > I never use NULL as a noun, or the name of a value; only as an
> > > adjective.
> >
> > I do not understand the adjective thing.
>
> Try this analogy: My sofa is blue. My shirt is blue. That doesn't mean
> that "my sofa" and "my shirt" are colours, or that they are the same /
> equal. In the same way, saying that <exp1> is null and <exp2> is null
> does not mean that <exp1> = <exp2>, or that they mean the same, or even
> that they denote the same kind of thing. I use "null" as an adjective,
> like "blue".

Sure, a one-argument predicate like 'is_null', or 'is_odd', talks about a property/attribute and can be called an 'adjective'. But the 'is_null' predicate cannot help one answer the question "what is '+' in '2 + NULL' ?". So, what is '+' in the expression and how does one interpret such expression ?

> --
> Jon
Received on Sun Dec 18 2005 - 18:26:14 CET