I''m working on a method but the results are "the opposite" of what I want to happen. Here''s what I have in my model: after_update :foo def foo self.scores.where(:standard_id => self.standard_ids).each do | score| score.destroy end end ... which actually deletes the scores I want to keep. What I want to do is something like: self.scores - self.scores.where(:standard_id => self.standard_ids).each do... OR a = self.scores b = self.scores.where(:standard_id => self.standard_ids) a - b = c c.each do... OR self.scores.reject(self.scores.where(:standard_id => self.standard_ids)).each do... Any help is greatly appreciated! Thanks in advance :-) -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.