[dba-SQLServer] NULLs

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.

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