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Received: by postgres.Berkeley.EDU (5.61/1.29)
	id AA22396; Fri, 24 Jul 92 15:31:09 -0700
Message-Id: <9207242231.AA22396@postgres.Berkeley.EDU>
From: postarch (Postgres Mailing Archive)
Subject: Re: How to retrieve only rows with null-values?
To: postgres@postgres.berkeley.edu
Sender: pg_adm@postgres.berkeley.edu
Reply-To: mer@postgres.berkeley.edu
In-Reply-To: Your message of "Thu, 23 Jul 92 05:20:01 PDT."
             <9207231220.AA03783@postgres.Berkeley.EDU> 
Date: Fri, 24 Jul 92 15:30:59 PDT

you write:

> I have a very simple question which I could not solve using the docs:
> 
> What is the correct Postquel syntax for retrieving only rows which
> have a null-value for a certain attribute?
> 
> I tried the obvious 'retrieve (test.all) where test.attr = NULL'
> but this only crashed the backend...

In version 4 you can say:

	retrieve (test.all) where test.attr ISNULL

In previous versions you could not test for null attributes.


Jeff Meredith
mer@postgres.berkeley.edu