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From: Theodore Petrosky <tedpet5@yahoo.com>
To: John Fabiani <johnf@jfcomputer.com>
To: Brent Dombrowski <brent.dombrowski@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Dates and NULL's`
Date: Tue, 10 May 2011 13:51:17 -0700 (PDT)
Message-ID: <177881.34459.qm@web111514.mail.gq1.yahoo.com> (raw)
In-Reply-To: <7E925851-8A86-4922-87D4-88F37F86C101@gmail.com>

If you think of it more like a null is an unknown. two unknowns can never be the same. they are unknown.

and a known date can never equal an UNknown date. if the unknown date is equal to a date, then it is known!!!!

my head hurts!!

Ted

--- On Tue, 5/10/11, Brent Dombrowski <brent.dombrowski@gmail.com> wrote:

> From: Brent Dombrowski <brent.dombrowski@gmail.com>
> Subject: Re: [SQL] Dates and NULL's`
> To: "John Fabiani" <johnf@jfcomputer.com>
> Cc: pgsql-sql@postgresql.org
> Date: Tuesday, May 10, 2011, 4:33 PM
> On May 10, 2011, at 9:48 AM, John
> Fabiani wrote:
> 
> > Hi,
> > Maybe this is a dumb question but if I have a date
> field that contains a NULL 
> > will it show up when I ask for a where date range for
> the same date field.
> > 
> > Where mydate >= "2011/04/01"::date and mydate<=
> "2011/04/30"::date
> > 
> > With the above where will the NULL's be selected????
> > 
> > I ask because I was always told that a NULL matches
> everything and nothing!
> > 
> > Johnf
> > 
> > -- 
> > Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
> > To make changes to your subscription:
> > http://www.postgresql.org/mailpref/pgsql-sql
> 
> 
> The NULLs will not be included. NULL matches nothing, not
> even itself.
> 
> Brent D.
> 
> 
> -- 
> Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-sql
> 



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