用了 DBUtils 更新部分不成功

//    改---<有问题>
    @Override
    public void update(Integer studentId, Studentinfo stu) {
        String sql = "update studentinfo set studentName=?,studentAge=? where studentId=?";
        QueryRunner qr = new QueryRunner(JDBCUtil.getDS());
        try {
            qr.update(sql, stu.getStudentName(), stu.getStudentAge(), stu.getStudentId());
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

//    修改指定学生信息   
    void update(Integer studentId, Studentinfo stu);

//    改 根据id修改信息
    @Test
    public void updata() {

        Studentinfo sinfo = new Studentinfo();
        sinfo.setStudentName("四大金刚");
        sinfo.setStudentAge(190);
        // 保存学生
        IStudentDao dao = new StudentinfoDaoImpl();
        dao.update(2019316, sinfo);
    }