gistfile1.rb

class Foo < ActiveRecord::Base
end

result_set = Foo.find_calculations(:conditions => ["active = ?", true]) do
  sum :field_one, :as => "sum_of_field_one"
  count :field_four
  max :field_one
  min :field_one
  mean :field_eight
end

result_set[:sum_of_field_one] # => 53
result_set[:field_four_count] # => 11
result_set[:field_one_max] # => 1535
result_set[:field_two_max] # => 144
result_set[:field_eight_mean] # => 94.314