code: def submit_plain_query(self, operation):
          
          self.messages = []
          self.cancel_if_pending()
          self.res_info = None
          logger.info("Sending query %s", operation[:100])
          w = self._writer
          with self.querying_context(tds_base.PacketType.QUERY):
              if tds_base.IS_TDS72_PLUS(self):
                  self._start_query()
              w.write_ucs2(operation)
docs: Sends a plain query to server.
  
          This call will transition session into pending state.
          If some operation is currently pending on the session, it will be
          cancelled before sending this request.
  
          Spec: http://msdn.microsoft.com/en-us/library/dd358575.aspx
  
          :param operation: A string representing sql statement.