Re: Differentiate Between Zero-Length String and NULLColumn Values

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?

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