Re: How to join when NULL is the common value ?

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Sat, 21 Oct 2000 00:20:39 +0200
Message-ID: <972134919.3696.1.pluto.d4ee154e@news.demon.nl>

<dili66_at_my-deja.com> wrote in message news:8sqcns$rjt$1_at_nnrp1.deja.com...
> Hi, At a first glance it appears that when someone
> would like to join two tables over some column then
> a row with a NULL value in one of the columns will
> not be joined with a row with a NULL value in
> the other table. Do you know if there is a switch
> to allow this type of join ?
>
> Thank you.
>
> D
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.

Null is nothing, by design in relational database systems. As null is nothing, you also can't compare null to null, and cases where columns at both ends are null, aren't meant to join at all. So what you say violates fundamental principles of relational theory, so no, there is no switch and it won't be there ever.

Regards,

Sybrand Bakker, Oracle DBA Received on Fri Oct 20 2000 - 17:20:39 CDT