On Wed, Jul 13, 2005 at 18:15:12 +0000,
markMLl.pgsql-general@xxxxxxxxxxxxxxx wrote:
> Many thanks Tom. Inconvenient from the point of view of the application but
> still useful information.
>
> The situation is that I've got a query with numerous subselects, each of which
> has to return exactly one row so I was doing a union with a nulled record then
> selecting the most recent: obviously I need to see bona-fide data if it's there.
you can order by datecol is null, datecol desc to get the most recent
non null date. For example:
area=> select day from (select 'today'::date as day union select 'tomorrow'::date as day union select null as day) as un order by day is null, day desc;
day
------------
2005-07-16
2005-07-15
(3 rows)
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
