gistfile1.txt

class Statistic < ActiveRecord::Base
  named_scope :by_month_and_year, :select => "DATE_FORMAT(created_at, '%b %y')", :group => "DATE_FORMAT(created_at, '%b %y')", :order => :created_at
end

>> Statistic.by_month_and_year.size
=> 6 # SELECT count(DATE_FORMAT(created_at, '%b %y')) AS count_date_format_created_at_b_y FROM `statistics`

>> Statistic.by_month_and_year.all.size
=> 5 # SELECT DATE_FORMAT(created_at, '%b %y') FROM `statistics` GROUP BY DATE_FORMAT(created_at, '%b %y') ORDER BY created_at