Re: Useful Oracle books - C.J. Date theory vs. practicality

Lex de Haan said,on my timestamp:29/05/2004 5:29 PM:

the IS NULL operator is two-valued,
so it would never show the "desired" behavior for this experiment...
'string' IS NULL always evaluates to FALSE, and '' IS NULL evaluates to TRUE
(which is quite unfortunate, but that's another discussion)

I see your point, of course. Otherwise it's harder to show the problem.

But the thing that bugs me is: isn't the Oracle (and presumably
others db) solution of "IS NULL" a good solution?

I mean: avoid the TRUE/FALSE/NULL logic problem without re-defining the
entire IF?

Is there something wrong with:
IF (<var> is NOT NULL) then
  IF(<var> = 'something') then do_this
  ELSE do_that
  END IF;
ELSE do_nothing;
END IF;
other than the obvious verbosity/style of writing?

(says he who had to code something like this ad-infinitum in a
project 3 years ago...)
--
Cheers
Nuno Souto
in sunny Sydney, Australia
dbvision@xxxxxxxxxxxxxxx
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