code: def _datalog(self, parameter, run, maxrun, det_id):
          "Extract data from database"
          values = {
              'parameter_name': parameter,
              'minrun': run,
              'maxrun': maxrun,
              'detid': det_id,
          }
          data = urlencode(values)
          content = self._get_content('streamds/datalognumbers.txt?' + data)
          if content.startswith('ERROR'):
              log.error(content)
              return None
          try:
              dataframe = read_csv(content)
          except ValueError:
              log.warning(
                  "Empty dataset"
              )    # ...probably. Waiting for more info
              return make_empty_dataset()
          else:
              add_datetime(dataframe)
              try:
                  self._add_converted_units(dataframe, parameter)
              except KeyError:
                  log.warning(
                      "Could not add converted units for {0}".format(parameter)
                  )
              return dataframf _datalog(self, parameter, run, maxrun, det_id):
          "Extract data from database"
          values = {
              'parameter_name': parameter,
              'minrun': run,
              'maxrun': maxrun,
              'detid': det_id,
          }
          data = urlencode(values)
          content = self._get_content('streamds/datalognumbers.txt?' + data)
          if content.startswith('ERROR'):
              log.error(content)
              return None
          try:
              dataframe = read_csv(content)
          except ValueError:
              log.warning(
                  "Empty dataset"
              )    # ...probably. Waiting for more info
              return make_empty_dataset()
          else:
              add_datetime(dataframe)
              try:
                  self._add_converted_units(dataframe, parameter)
              except KeyError:
                  log.warning(
                      "Could not add converted units for {0}".format(parameter)
                  )
              return dataframe
docs: Extract data from database