Allow user to set or update config values in the database table.
    This is always called if no valid entry exists in the table already.

    Parameters
    ----------
      configKey : string
        Name of config field.

      strDescriptor : string
        Description of config field.

      isDir : boolean [optional : default = True]
        Set to True if config value is
        expected to be a directory path.

      dbConfigValue : string [optional : default = None]
        The value of an existing entry
        for the given config field.

    Returns
    ----------
      string
        New value for given config field in database.

def _UserUpdateConfigValue(self, configKey, strDescriptor, isDir = True, dbConfigValue = None):
    """
    Allow user to set or update config values in the database table.
    This is always called if no valid entry exists in the table already.

    Parameters
    ----------
      configKey : string
        Name of config field.

      strDescriptor : string
        Description of config field.

      isDir : boolean [optional : default = True]
        Set to True if config value is
        expected to be a directory path.

      dbConfigValue : string [optional : default = None]
        The value of an existing entry
        for the given config field.

    Returns
    ----------
      string
        New value for given config field in database.
    """
    newConfigValue = None

    if dbConfigValue is None:
      prompt = "Enter new {0} or 'x' to exit: ".format(strDescriptor)
    else:
      prompt = "Enter 'y' to use existing {0}, enter a new {0} or 'x' to exit: ".format(strDescriptor)

    while newConfigValue is None:
      response = goodlogging.Log.Input("CLEAR", prompt)

      if response.lower() == 'x':
        sys.exit(0)
      elif dbConfigValue is not None and response.lower() == 'y':
        newConfigValue = dbConfigValue
      elif not isDir:
        newConfigValue = response
        self._db.SetConfigValue(configKey, newConfigValue)
      else:
        if os.path.isdir(response):
          newConfigValue = os.path.abspath(response)
          self._db.SetConfigValue(configKey, newConfigValue)
        else:
          goodlogging.Log.Info("CLEAR", "{0} is not recognised as a directory".format(response))

    return newConfigValue