On Mon, Jul 27, 2009 at 10:51:00PM -0700, Nick wrote:
> Is it possible to join two tables by the nearest date? For example how
> could I find out where the user was on their birthday?
DISTINCT ON[1] is normally the easiest way:
SELECT DISTINCT ON (u.id) u.id, l.id, l.created
FROM users u, users_locations l
WHERE u.id = l.user_id
AND u.birthday <= l.created
ORDER BY u.id, l.created
Untested, but hopefully gives enough hints about where to look!
--
Sam http://samason.me.uk/
[1] http://www.postgresql.org/docs/current/static/sql-select.html#SQL-DISTINCT
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