pk_and_sequence_for

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 620
      def pk_and_sequence_for(table)
        execute_and_free("SHOW CREATE TABLE #{quote_table_name(table)}", 'SCHEMA') do |result|
          create_table = each_hash(result).first[:"Create Table"]
          if create_table.to_s =~ /PRIMARY KEY\s+(?:USING\s+\w+\s+)?\((.+)\)/
            keys = $1.split(",").map { |key| key.delete('`"') }
            keys.length == 1 ? [keys.first, nil] : nil
          else
            nil
          end
        end
      end