[thelist] ASP & SQL

Paul Cowan evolt at funkwit.com
Thu Sep 12 23:31:00 CDT 2002


Joshua Olson wrote:
> There's definitely a difference from having a problem with NULL's and
> acknowledging that some people will be overwhelmed when trying to
> incorporate them into the conditionals of a query.  I agree, they are
> nice... but, they can complicate conditionals fairly quickly--adding even
> more wonderful OR's to the clause--unless you truly understand them.

What?

((fname = <varFName>) OR (COALESCE(<varFName>, '') = ''))

Hehe.

And yeah, you're both right. NULLs rule, but just try explaining boolean
logic using NULLs to people who don't get them. Most people get
    true AND <null> is unknown
    false OR <null> is unknown
    etc...

and, eventually, grok that
    1 = <null> is unknown, but
    1 <> <null> is unknown


but then, when they think they've got it worked out, get very confused by
    true OR <null> is true
    false AND <null> is false
    etc...


Use nulls wisely, my children.

Paul





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