Re: Multiplicity, Change and MV
Date: Tue, 18 Apr 2006 16:18:18 +0300
Message-ID: <e22ot8$19e$1_at_emma.aioe.org>
> >
> > 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 - 15:18:18 CEST