在Java中实现增、删、改、查功能

//添加操作
    public void btnInsert_actionPerformed(ActionEvent e) {
        String name = this.txtName.getText().trim();
        String sex = this.txtSex.getText().trim();
        String grade = this.txtGrade.getText().trim();
        String score = this.txtScore.getText().trim();
        if (name.equals("") || sex.equals("") || grade.equals("") ||
            score.equals("")) {
            JOptionPane.showMessageDialog(this, "您输入的不合法!");
        }
        String sqlString = "insert into Score values('" + name + "','" + sex +
                           "','" + grade + "','" + score + "')";
        int rows = db.exeUpdate(sqlString);
        if (rows == 0) {
            JOptionPane.showMessageDialog(this, "添加失败！");
        } else {
            JOptionPane.showMessageDialog(this, " 添加成功！ ");
        }
    }


    //删除操作
    public void btnDelect_actionPerformed(ActionEvent e) {
        String name = this.txtName.getText().trim();
        if (name.equals("")) {
            JOptionPane.showMessageDialog(this, "你输入的数据不完整");
            return;
        }
        String sqlString = "delete from Score where Name='" + name + "'";
        int rows = db.exeUpdate(sqlString);