Concise SQL generation

def self.create_from_array(attrs)

  keys = attrs.first.keys

  d = ActiveRecord::Base.connection

   d.execute <<SQL

    INSERT INTO #{table_name} (#{keys * ', '}, created_at, updated_at)

    VALUES #{attrs.map do |a|
      "(#{keys.map{|k| d.quote(a[k].to_s)} * ','},

          NOW(),

          NOW())"}

    ON DUPLICATE KEY UPDATE #{keys.map{|k| "#{k} = VALUES(#{k})"} * ', '}

SQL

end