同名model导致的Invalid operation for the current cursor position

 使用分隔面板,在面板的上下区间内,各做一个表格显示数据库的数据,上区表格点击任意行时,下去表格根据选中的行找出与之对应的另一个表中的数据集.(在我的OA项目--客户管理中实现)

以下是抽取的两个表格显示的方法:

private void tup(String Tsql) {
  String sql;
  db = new dbsql();
  db.connect();
  if (Tsql.equals(" "))
   sql = "select 客户编号=CID,客户名称=Cname,联系电话=Ctel,邮件=Cmail,公司地址=Cdz from client";
  else
   sql = "select 客户编号=CID,客户名称=Cname,联系电话=Ctel,邮件=Cmail,公司地址=Cdz from client";

  rs = db.query(sql);

  modelup = new ResultSetTableModel(rs);

  panel_up = new JPanel();
  panel_up.setLayout(new BorderLayout());
  splitPaneVR.setLeftComponent(panel_up);

  scrollPane_up = new JScrollPane();
  panel_up.add(scrollPane_up, BorderLayout.CENTER);

  table_up = new JTable(modelup);
  table_up.addMouseListener(new MouseAdapter() {
   public void mouseClicked(final MouseEvent arg0) {
    int row = table_up.getSelectedRow(); // 获得当前选中的行号
    ID = modelup.getValueAt(row, 0);
   }
  });
  scrollPane_up.setViewportView(table_up);
 }

 private void tdown(String Dsql) {
  String sql;
  db = new dbsql();
  db.connect();
  if (Dsql.equals(" "))
   sql = "select 联系人编号=TID,姓名=Tname,性别=Tsex,联系电话=Ttel,邮件=Tmail,所属部门=Tdept from contact";
  else
   sql = "select 联系人编号=TID,姓名=Tname,性别=Tsex,联系电话=Ttel,邮件=Tmail,所属部门=Tdept from contact";

  rs = db.query(sql);

  modeldown = new ResultSetTableModel(rs);

  panel_down = new JPanel();
  panel_down.setLayout(new BorderLayout());
  splitPaneVR.setRightComponent(panel_down);

  scrollPane_down = new JScrollPane();
  panel_down.add(scrollPane_down, BorderLayout.CENTER);

  table_down = new JTable(modeldown);
  scrollPane_down.setViewportView(table_down);
 }

以上红字部分修改前都是model,结果运行时出现异常,Invalid operation for the current cursor position--游标位于结果集首行之前,后来修正后正常.