Обсуждение: Null and Not Null

** Reply Requested When Convenient **

Can some one please help me understand Null and Not Null

Thanks

Mike Hammonds, CNE5, MCP-NT
Fellon-McCord & Associates, Inc.
Office:  502.214-6324
Fax:      502.426.8800
mhammonds@knowledgeinenergy.com
Show Me the Code!!

Hi Mike,

Your question is sort of broad.  Could you be more specific?

However, a general reply to your broad question (and a source of confusion
for many people) is that Null does not mean "empty", rather it means
"undefined" (as in "the answer to a poorly formed question") -- which is why
Null = Null is false.

Thanks,
David Boerwinkle

----- Original Message -----
From: Mike Hammonds <mhammonds@knowledgeinenergy.com>
To: <pgsql-novice@postgresql.org>
Sent: Tuesday, December 26, 2000 9:43 AM
Subject: [NOVICE] Null and Not Null


** Reply Requested When Convenient **

Can some one please help me understand Null and Not Null

Thanks

Mike Hammonds, CNE5, MCP-NT
Fellon-McCord & Associates, Inc.
Office:  502.214-6324
Fax:      502.426.8800
mhammonds@knowledgeinenergy.com
Show Me the Code!!

Look at http://www.comptechnews.com/~reaster/dbdesign.html#three-valued-logic
Might be helpful.

On Tuesday 26 December 2000 10:43, Mike Hammonds wrote:

> > ** Reply Requested When Convenient **
>
> Can some one please help me understand Null and Not Null
>
> Thanks
>
> Mike Hammonds, CNE5, MCP-NT
> Fellon-McCord & Associates, Inc.
> Office:  502.214-6324
> Fax:      502.426.8800
> mhammonds@knowledgeinenergy.com
> Show Me the Code!!

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