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From: Thomas F.O'Connell <tfo@sitening.com>
Subject: Re: Making NULL entries appear first when ORDER BY <field> ASC
Date: Wed, 23 Feb 2005 14:22:41 -0600
To: Bruno Wolff III <bruno@wolff.to>
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Yup. Got it. Wasn't thinking clearly about what expression meant. 
Thanks!

-tfo

--
Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC
http://www.sitening.com/
110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-260-0005

On Feb 23, 2005, at 2:33 PM, Bruno Wolff III wrote:

> On Wed, Feb 23, 2005 at 13:54:50 -0600,
>   "Thomas F.O'Connell" <tfo@sitening.com> wrote:
>> How would one know from the reference material that it is possible to
>> include IS NOT NULL in an ORDER BY clause?
>>
>> Similarly, other than the FAQ, I've never been able to tell from the
>> SELECT documentation why ORDER BY random() works.
>
> From the SELECT command documentation:
> SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]
>     * | expression [ AS output_name ] [, ...]
>     [ FROM from_item [, ...] ]
>     [ WHERE condition ]
>     [ GROUP BY expression [, ...] ]
>     [ HAVING condition [, ...] ]
>     [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]
>     [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
>     [ LIMIT { count | ALL } ]
>     [ OFFSET start ]
>     [ FOR UPDATE [ OF table_name [, ...] ] ]
>
> Notice that for ORDER BY you can supply an expression. That should be 
> a big
> clue why you can use IS NOT NULL and random() in an ORDER BY clause.