login help - grouping records

hello,
  check this post :
http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/921051b1844a1ddd/93cfa15e7c907e00?lnk=gst&q=month#93cfa15e7c907e00
almost the same thing you want to do (except it is per monthes not per
days).

your query should look like it:
Post.find :all, :group => "DATE_FORMAT(date,'%Y-%m-%d')"

i'm not sure about DATE_FORMAT synthax, it is a mysql function but
psql user you must check it.