code: private String update() {
  		// If this has been done before, there is no change in checkSum and the last time notified is within GracePeriod
  		if(checksum!=0 && checksum()==checksum && now < last.getTime()+graceEnds && now > last.getTime()+lastdays) {
  			return null;
  		} else {
  			return "UPDATE authz.notify SET last = '" +
  					Chrono.dateOnlyStamp(last) +
  					"', checksum=" +
  					current +
  					" WHERE user='" +
  					user + 
  					"' AND type=" +
  					type.getValue() +
  					";";
  		}
  	}
docs: Returns an Update String for CQL if there is data.
  
  Returns null if nothing to update
  @return