http://encabine.com/wp-config-sample.php~ How to select the first/least/max row per group in SQL

http://olhg45.fr/jklz/cialis-10mg-boite-de-4-prix A nice explanation about the subject. Easy to understand.
http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/