我有一个JComboBox,它从数据库检索数据并将其显示在JTable中。除了将来自不同数据库的数据合并到JTable中之外,其他所有内容都运行良好。您是否知道如何仅显示特定数据库的数据?谢谢!

下面是我使用的代码。

  private void comBoxActionPerformed(java.awt.event.ActionEvent evt)
  {
        if (comBox.getSelectedItem() == "Select . . .") {

        } else if (comBox.getSelectedItem() == "Students") {
        DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
        String sql = "select * from students";
        try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});
        }
    } catch(SQLException e){
        e.printStackTrace();
    }
    } else if (comBox.getSelectedItem() == "Teachers"){
    DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
    String sql = "select * from teachers";
    try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});

        }
    } catch(SQLException e){
        e.printStackTrace();
    }
    } else if (comBox.getSelectedItem() == "Directors") {
    DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
    String sql = "select * from directors";
    try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});

        }
    } catch(SQLException e){
        e.printStackTrace();
    }
    }
}                                 `


这是程序的output

我将不胜感激。谢谢!

最佳答案

您正在调用model.addRow(),它将在现有数据模型上添加新行。它不会在任何地方清除数据模型。因此,这些行将被追加到先前的数据中。您需要将数据模型设置为新模型或首先删除现有数据。

10-07 19:05
查看更多