Re: Group By Questions..

From: David Cressey <David_at_DCressey.com>
Date: Sun, 3 Oct 1999 06:52:50 -0400
Message-ID: <cPGJ3.435$x4.47274@petpeeve.ziplink.net>

A NULL is never equal to a NULL. A NULL is also never unequal to a NULL. This is strange, but true.

When you allow predicates involving NULLS, you get into three valued logic.

Try a few queries involving tests for equality between objects, and see how the
test comes out when the attribute being tested is NULL.

Frank Hubeny wrote in message <37F60875.BB49A27_at_ntsource.com>...
>
>If the nulls are consistently considered either equal or not equal, then
the
>results should still be the same, ignoring order. Oracle appears to
>consider null to equal null when constructing the groups as shown below:
>
Received on Sun Oct 03 1999 - 05:52:50 CDT