code: public boolean refreshSession (String sessionKey, int expireDays)
          throws PersistenceException
      {
          Calendar cal = Calendar.getInstance();
          cal.add(Calendar.DATE, expireDays);
          Date expires = new Date(cal.getTime().getTime());
  
          // attempt to update an existing session row, returning true if we found and updated it
          return (update("update sessions set expires = '" + expires + "' " +
                         "where authcode = " + JDBCUtil.escape(sessionKey)) == 1);
      }
docs: Validates that the supplied session key is still valid and if so, refreshes it for the
  specified number of days.
  
  @return true if the session was located and refreshed, false if it no longer exists.