Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation

"Cimode" <cimode_at_hotmail.com> wrote in message news:1177938789.949723.62480_at_h2g2000hsg.googlegroups.com...
> On Apr 30, 1:56 pm, "Brian Selzer" <b..._at_selzer-software.com> wrote:
> > "Cimode" <cim..._at_hotmail.com> wrote in message
> [Snipped]
> > I'm not sure I understand you. Missing information is a problem
independent
> > of any implementation.
> Sure but NULL is only one way to handle missing information and it is
> one that does not fall into 2VL required by RM.

Why does NULL not fit into 2VL? I've never propoerly understood this.

In practice, I've been willing to use NULLS in databases rather than decompose tables to eliminate the need for NULLS. And I've tended to avoid SQL 3VL, by forumlating my queries carefully.

But I've never fully studied the question. Once you accept NULLS as (one way) of dealing with missing data, are you then forced, willy nilly, into 3VL for your DML? It's not obvious to me, even though that's what SQL did. Received on Mon Apr 30 2007 - 08:21:47 CDT