ผมมีปัญหาเรื่องการทำแบบทดสอบ online อยากขอคำแนะนำด้วยครับ

<?php
$var = $_GET["var"]; // แบบ get

$var = $_POST["var"]; // แบบ post

$var = $_REQUEST["var"];// ได้ทั้ง get และ post
?>

<?php
$select = $_POST["select_".$id];
if($select==$answer) 
?>

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

namespace Elearning
{
    public partial class sSubjectTest : System.Web.UI.Page
    {
        protected string PostBackStr;

        public string TestID;

        DBConnect DB = new DBConnect();

        protected void Page_Load(object sender, EventArgs e)
        {

            txtName.Text = Session["Name"].ToString();
            PostBackStr = Page.ClientScript.GetPostBackEventReference(this, "time");
            if (IsPostBack)
            {
                TestID = Request.QueryString["TestID"].ToString();

                string eventArg = Request["__EVENTARGUMENT"];
                if (eventArg == "time")
                {
                    getNextQuestion();
                }
            }
        }
        protected void Button1_Click(object sender, EventArgs e)
        {
            Label1.Visible = false;
            txtName.Visible = false;
            Button1.Visible = false;
            Panel1.Visible = true;
            lblName.Text = "Name : " + txtName.Text;
            int score = Convert.ToInt32(txtScore.Text);
            lblScore.Text = "Score : " + Convert.ToString(score);
            Session["counter"] = "1";
            Random rnd = new Random();
            int i = rnd.Next(1, 10);//Here specify your starting slno of question table and ending no.
            //lblQuestion.Text = i.ToString();
            getQuestion(i);

        }
        protected void Button2_Click(object sender, EventArgs e)
        {
            getNextQuestion();
        }
        public void getQuestion(int no)
        {
            string str = "select * from [QA] where TestID = " + TestID;

            //SqlDataAdapter da2 = new SqlDataAdapter(str, sqlconn);
            DataSet ds2 = new DataSet();
            //da2.Fill(ds2, "Question");

            ds2 = DB.QueryDataSet(str);

            if (ds2.Tables[0].Rows.Count > 0)
            {
                DataRow dtr;
                int i = 0;
                while (i < ds2.Tables[0].Rows.Count)
                {
                    dtr = ds2.Tables[0].Rows[i];

                    Session["Answer"] = Convert.ToString(Convert.ToInt32(dtr["Correct"].ToString()) - 1);

                    Session["Marker"] = dtr["Marker"].ToString();

                    lblQuestion.Text = "Q." + Session["counter"].ToString() + "  " + dtr["Question"].ToString();
                    RblOption.ClearSelection();
                    RblOption.Items.Clear();
                    RblOption.Items.Add(dtr["Option1"].ToString());
                    RblOption.Items.Add(dtr["Option2"].ToString());
                    RblOption.Items.Add(dtr["Option3"].ToString());
                    RblOption.Items.Add(dtr["Option4"].ToString());
                    i++;
                }
            }

            DB.Close();

            getNextQuestion();

        }
        public void getNextQuestion()
        {
            if (Convert.ToInt32(Session["counter"].ToString()) < 10)//10 is a counter which is used for 10 questions
            {
                if (RblOption.SelectedIndex >= 0)
                {
                    if (Session["Answer"].ToString() == RblOption.SelectedIndex.ToString())
                    {
                        int score = Convert.ToInt32(txtScore.Text) + 1;// 1 for mark for each question
                        //   txtScore.Text = score.ToString();
                        lblScore.Text = "Score : " + Convert.ToString(score);
                    }
                    else
                    {
                        string a = "<script>alert('คุณตอบผิดค่ะ คำอธิบายข้อนี้คือ " + Session["Marker"].ToString() + "')</script>";
                        Response.Write(a);
                    }
                }

                Random rnd = new Random();
                int i = rnd.Next(1, 10);
                //lblQuestion.Text = i.ToString();
                getQuestion(i);
                Session["counter"] = Convert.ToString(Convert.ToInt32(Session["counter"].ToString()) + 1);

            }
            else
            {
                Panel2.Visible = false;
                //code for displaying after completting the exam, if you want to show the result then you can code here.
            }
        }
    }
}