Re: modeling either/or relationship...
From: -CELKO- <jcelko212_at_earthlink.net>
Date: 2 Feb 2006 11:51:11 -0800
Message-ID: <1138909871.293993.53890_at_z14g2000cwz.googlegroups.com>
Date: 2 Feb 2006 11:51:11 -0800
Message-ID: <1138909871.293993.53890_at_z14g2000cwz.googlegroups.com>
>> Still, I get this strange feeling thinking about NULLs in UNIQUE. <<
We did, too. I can only vaguely remember the arguements in X3H2 now.
Basically, we said that there is equality and there is grouping, as in GROUP BY. NULLs fail equality, but get grouped together. The REFERENCES clause uses grouping and not equality.
As we used to say about OS/JCL, it makes perfect sense after you work with it for decade :) Received on Thu Feb 02 2006 - 20:51:11 CET