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() +
					";";
		}
	}
private String update ( ) { 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 ( ) + ";" ; } }
Returns an Update String for CQL if there is data.

Returns null if nothing to update
@return