Bruger seneste aktiviteter - PHP MySQL

En MySQL UNION-forespørgsel kunne fungere her:

(SELECT `user_id`, `date_added`, 'photo' AS `type` FROM `photos` WHERE `user_id` = uid) UNION
 (SELECT `user_id`, `date_added`, 'video' AS `type` FROM `videos` WHERE `user_id` = uid) UNION
 (SELECT `user_id`, `date_added`, 'comment' AS `type` FROM `comments` WHERE `user_id` = uid)
 ORDER BY `date_added` DESC;

Så ville du ende med et resultatsæt som

user_id | date_added | type
    5   | 2009-01-03 | photo
    5   | 2008-12-07 | video
    5   | 2008-11-19 | comment

og så videre. (faktisk kan du forlade user_id ud af SELECT, hvis du vil, selvfølgelig)