Re: Making NULL entries appear first when ORDER BY <field> ASC

On Wed, Feb 23, 2005 at 13:54:50 -0600,
"Thomas F.O'Connell" <tfo(at)sitening(dot)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.