Dan Waters
dwaters at usinternet.com
Mon Mar 16 11:56:45 CDT 2009
It's Null - but your data validation must ensure that one of the two fields is correctly filled in. I see data validation as not applying to just single fields, but also applying to combinations of fields. Dan -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com] On Behalf Of Susan Harkins Sent: Monday, March 16, 2009 11:39 AM To: Discussion concerning MS SQL Server Subject: Re: [dba-SQLServer] NULLs So, what's the value of the unused field for each patient? Susan H. > If I was designing that system, I would have two fields. One is the SSN, > the other is a unique hospital defined number for people without a SSN. > Either could be Null, but one of them must be filled in correctly. And > neither could be a FK. _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com