Я создаю приложение викторины с использованием c#. как написать код, чтобы получить секретный вопрос

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я создал приложение викторины, я хочу добавить кнопку privious, чтобы получить вопрос.

Что я уже пробовал:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class ExamHome : Form
    {
        int timeleft;
        int seconds;
              int q = 1;
        public ExamHome()
        {
            InitializeComponent();
        }
        SqlConnection con = new SqlConnection("uid=sa;password=1234;server=anjibabu;database=examportal");
        private void button1_Click(object sender, EventArgs e)
        {
            if (comboBox1.Text == "Daily Test")
            {
                timeleft = 20;
                seconds = 60;
                label5.Text = "20 MINUTES";
            }

            else if (comboBox1.Text == "Grand Test")
            {
                timeleft = 40;
                seconds = 60;
                label5.Text = "40 MINUTES";
            }

            if (comboBox1.Text == "")
            {
                MessageBox.Show("Please Select Exam Type!");



            }
            else if (comboBox2.Text == "")
            {
                MessageBox.Show("Please Select Subject!");
            }
            else
            {
                timer1.Start();
             
                label1.Visible = false;
                label2.Visible = false;
                panel1.Visible = true;
                button2.Visible = true;
                button1.Visible = false;
                groupBox1.Visible = true;
                comboBox1.Visible = false;
                comboBox2.Visible = false;

                SqlCommand cmd1 = new SqlCommand("SELECT MAX(slNO) FROM MQ2 WHERE Subject='" +comboBox2 .SelectedItem  + "'", con);
                SqlCommand cmd2 = new SqlCommand("SELECT MIN(slNO) FROM MQ2 WHERE Subject='" +comboBox2 .SelectedItem + "'", con);
                con.Open();
                int count = (int)cmd1.ExecuteScalar();
                int sc = (int)cmd2.ExecuteScalar();
                Random rnd = new Random();
                int i = rnd.Next(sc, count);//Here specify your starting slno of question table and ending no.

                getQuestion(i);
            }
        }

        private void ExamHome_Load(object sender, EventArgs e)
        {
            panel1.Visible = false;
            button2.Visible = false;
            groupBox1.Visible = false;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            q++;
            getNextQuestion();
        }
        public void getQuestion(int no)
        {


            string str = "select * from MQ2 where slNo=" + no + " ";
            SqlDataAdapter da2 = new SqlDataAdapter(str, con);
            DataSet ds2 = new DataSet();
            da2.Fill(ds2, "MQ2");
            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];
                    label3.Text = "Q." + q.ToString();
                    label4.Text = dtr["Question"].ToString();
                    radioButton1.Text = dtr["Option1"].ToString();
                    radioButton2.Text = dtr["Option2"].ToString();
                    radioButton3.Text = dtr["Option3"].ToString();
                    radioButton4.Text = dtr["Option4"].ToString();
                    i++;


                }
            }

        }
        public void getNextQuestion()
        {
            if (comboBox1.Text == "Daily Test")
            {


                SqlCommand cmd2 = new SqlCommand("SELECT MAX(slNO) FROM MQ2 WHERE Subject='" + comboBox2.SelectedItem + "'", con);
                SqlCommand cmd1 = new SqlCommand("SELECT MIN(slNO) FROM MQ2 WHERE Subject='" + comboBox2.SelectedItem + "'", con);
                int sc = (int)cmd1.ExecuteScalar();
                int count = (int)cmd2.ExecuteScalar();
                if (q <= 10)
                {
                    Random rnd = new Random();
                    int i = rnd.Next(sc, count);

                    getQuestion(i);
                    if (q == 10)
                    {
                        button2.Text = "Finish";
                        
                    }
                }
                else
                {
                    timer1.Stop();
                    this.Hide();
                    Home h = new Home();
                    h.Visible = true;
                   
                }


            }
            else if (comboBox1.Text == "Grand Test")
            {

                SqlCommand cmd2 = new SqlCommand("SELECT MAX(slNO) FROM MQ2 WHERE Subject='" + comboBox2.SelectedItem + "'", con);
                SqlCommand cmd1 = new SqlCommand("SELECT MIN(slNO) FROM MQ2 WHERE Subject='" + comboBox2.SelectedItem + "'", con);
                int sc = (int)cmd1.ExecuteScalar();
                int count = (int)cmd2.ExecuteScalar();
                if (q <= 20)
                {
                    Random rnd = new Random();
                    int i = rnd.Next(sc, count);

                    getQuestion(i);
                    if (q == 20)
                    {
                        button2.Text = "Finish";
                    }
                }
                else
                {
                    timer1.Stop();
                    this.Hide();
                    Home h = new Home();
                    h.Visible = true;
                }

            }
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
           
                if (timeleft > 0)
                {
                    timeleft = timeleft - 1;
                    label5.Text = timeleft + "" + "MINUTES";
              }
                else
                {
                    timer1.Stop();
                    MessageBox.Show("Time Up!");
                    this.Hide();
                    Home h = new Home();
                    h.Show();

                }

               
            }

        private void timer2_Tick(object sender, EventArgs e)
        {
            if (seconds > 0)
            {
                seconds = seconds - 1;
                label5.Text = timeleft + "::" + seconds;
            }

           
        }
        

    }
}

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