Re: Informix Certified Professional Program

This is another confusing point when dealing with nulls. Even though comparing something to null yelds null, in many situations (if or case statements, mainly) 4gl will [correctly!] behave the same way it would had the comparison returned false, and this can be source of confusion and false beliefs. My Lit.30 Marco ____________________________________________________________________________ rem radioterapia, which I immeritately manage, seldom agrees with what I say marco greco (Catania, Italy) Work: marcog@ctonline.it rem radioterapia 39 95 447828 fax 446558 (was mar.greco@agora.stm.it) Achea 39 95 503117 --- On Tue, 11 Feb 1997 19:21:27 -0800 Jonathan Leffler <johnl@informix.com> }From: Ian Goddard <igoddard@netcomuk.co.uk> }Date: Wed, 12 Feb 1997 01:06:47 -0800 }X-Informix-List-Id: <news.33791> } }Walter S. Tyszka wrote: } }> According to Informix: NULL means unknown, so comparing anything to NULL }> will evaluate as true - since you can not tell for sure whether the two } ^^^^ }Since when? We went over this a few months ago. It evaluates to false. ^^^^^ Since when? I went over this earlier today, and it evaluates to unknown! }> values are different. Yours pedantically, Jonathan Leffler (johnl@informix.com) #include <disclaimer.h> -----------------End of Original Message-----------------