code: public void update(Connection conn, User user) throws SQLException {
          String sql = "UPDATE userbase \n";
          Integer id = user.getId();
          user.setId(null);
          try {
              String s = SQLBuilder.beanToSQLClause(user,",");
              sql = sql + SQLBuilder.getSetClause(s) +"\n"+
                  "WHERE id=? ";
          } catch (JibuException e) {
              throw new SQLException(e.getMessage());
          }
          user.setId(id);
          run.update(conn, sql, id);
      }
docs: {@inheritDoc}
  <p>
  除 id 属性以外，所有非空的属性将会被更新至数据库中。</p>