# File lib/rubyrep/connection_extenders/mysql_extender.rb, line 10
      def primary_key_names(table)
        row = self.select_one("select table_name from information_schema.tables\nwhere table_schema = database() and table_name = '\#{table}'\n")
        if row.nil?
          raise "table '#{table}' does not exist"
        end
        
        rows = self.select_all("select column_name from information_schema.key_column_usage\nwhere table_schema = database() and table_name = '\#{table}'\nand constraint_name = 'PRIMARY'\norder by ordinal_position\n")

        columns = rows.map {|_row| _row['column_name']}
        columns
      end