Re: Multiplicity, Change and MV

"Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message news:tx51g.61657$VV4.1151645_at_ursa-nb00s0.nbnet.nb.ca...
> x wrote:

> >
> > There is nothing bad about nulls.

> I suggest you check out the various _Writings..._ books by Chris Date.
> The flaws in NULL and NVL for N > 2 have been well-argued.

They have been argued in prose. I prefer mathematics. I see nothing wrong using a boolean algebra with more than 2 values. Actually using only 2 values feels like using machine code. :-) I see nothing wrong using a boolean algebra with uncountable many values. This in theory. I practice things may differ.

> > Only the SQL style null is bad.
> > You can choose if you prefer to use relations with nulls or sets of
> > relations.

> Unfortunately, if your DMBS has to allow for NULL, it will generally not
> function as well as one that does not. Even if the DBMS implementation
> detects all cases without NULL for optimization purposes, the DBMS will
> require more executable code and have more branches of execution. As a
> general rule, these properties will translate into slower code (ie. more
> page faults) and buggier code (ie. less complete coverage during testing).

Write once, debug a lifetime, die. :-)
In theory a DBMS will not have bugs. :-) Received on Tue Apr 18 2006 - 08:18:18 CDT