Re: Differentiate Between Zero-Length String and NULLColumn Values

["D'Arcy J.M. Cain" <darcy(at)druid(dot)net>]

On Tue, 30 Jan 2007 09:23:32 -0500
Andrew Sullivan <ajs(at)crankycanuck(dot)ca> wrote:
> Hmm.  Well, I'm not an Oracle guy, so I don't really know.  All I
> know is that we occasionally get people coming from Oracle who are
> surprised by this difference.  What I've been _told_ is that '' and
> NULL are under some circumstances (maybe integers?) the same thing,
> whereas of course ' ' and NULL are not.  But since I'm not an Oracle
> user, people should feel free to ignore me :)

I don't have an Oracle installation here and I haven't used it much but
I wonder if they treat the following two statements differently.

   SELECT * FROM table WHERE column IS NULL;
   SELECT * FROM table WHERE column = NULL;

The latter violates the SQL spec and is not allowed by PostgreSQL
without setting a special flag.  Is it possible that Oracle accepts "="
against NULL and also treats it slightly differently?

-- 
D'Arcy J.M. Cain <darcy(at)druid(dot)net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.