activity.rb

def batch_add(users, activity_type, target)
  return false if users.blank? or activity_type.blank? or target.blank?
  inserts = []
  users.each {|user| inserts.push "('#{user.id}', '#{activity_type}', '#{target.id}', '#{target.class}', UTC_TIMESTAMP())" }

  sql = "INSERT INTO activities (`user_id`, `activity_type`, `target_id`, `target_type`, `created_at`) VALUES #{inserts.join(", ")}"
  ActiveRecord::Base.connection.execute sql
end