Re: SQL IF

"Matt B." wrote:
>
> "Mike Dwyer" <dwyermj_at_co,larimer.co.us> wrote in message
> news:LzM15.111$p62.48322_at_wdc-read-01.qwest.net...
> > By definition, NULL is "unknown." It isn't that Oracle doesn't "know what to
> > do with it," but an unknown cannot be compared to a known value.
>
> But hasn't Oracle opted to treat it that way (are all programming languages and
> database languages like that)?
>
> I'll work w/it of course, but in my own mind if X is '1' and Y is null,
> therefore X does not equal Y and Y does not equal X. Y may be null and an
> unknown, but whatever it is, is for sure isn't '1'! :-)

SQL (and most other programming languages which include the concept of NULL or an unknown value) uses three valued logic, not two valued. This is the basis of the difference. Almost any combination with an unknown gives an unknown. Received on Thu Jun 15 2000 - 00:00:00 CEST