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

On Apr 30, 2:21 pm, "David Cressey" <cresse..._at_verizon.net> wrote:
> "Cimode" <cim..._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.
I suggest you read on POCW and understand the concepts of proposition/ predicates. F Pascal explains it very well in Practical Issues in Database Management.

> 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.
As far as I am concerned, in the past 10 years I have not designed one database with NULL values. Sure I had to add a few table here and there at design time only (+ make some adjustments) but the advantages of *not* using NULLS at all encompass drawbacks by light years. And I can say there is a huge difference both in performance and reliability. NULLS are like cigarettes, once you remember that there is a life without them, you'd better stop smoking.

Regards... Received on Mon Apr 30 2007 - 15:30:06 CEST