在测试问题中循环进行失败

编辑 -我最初发布了我的代码的早期版本，现在更正代码

我有一个测试问题的数据库表，我在我的表格中显示，但是，当我得到表中的最后一个问题时，我得到以下错误:

IndexOutOfRangeException was unhandled
There is no row at position 5

我的表结构是这样的:

问题编号|问题|答案1 |答案2 |答案3 |答案4 |正确答案

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
using System.Data.SqlClient;
namespace WindowsFormsApplication1
{
public partial class QuizQuestions : Form
{
    public WindowsAnalysisQuiz()
    {
        InitializeComponent();
    }
    //int questionNumber;
    String correctAnswer;
    private void WindowsAnalysisQuiz_Load(object sender, EventArgs e)
    {
        //declare connection string using windows security
        string cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:''Users''Hanna''Desktop''QuizQuestions.accdb";
        //declare Connection, command and other related objects
        OleDbConnection conGet = new OleDbConnection(cnString);
        OleDbCommand cmdGet = new OleDbCommand();
        //try
        //{
        //open connection
        conGet.Open();
        //String correctAnswer;
        cmdGet.CommandType = CommandType.Text;
        cmdGet.Connection = conGet;
        cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()"; 
        OleDbDataReader reader = cmdGet.ExecuteReader();
        reader.Read();
        label1.Text = reader["Question"].ToString();
        radioButton1.Text = reader["Answer 1"].ToString(); 
        radioButton2.Text = reader["Answer 2"].ToString();
        radioButton3.Text = reader["Answer 3"].ToString();
        radioButton4.Text = reader["Answer 4"].ToString();
        correctAnswer = reader["Correct Answer"].ToString();
        //questionNumber = 0;
        conGet.Close();
    }
    private void btnNextQuestion_Click(object sender, EventArgs e)
    {
        String cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:''Users''Hannah''Desktop''QuizQuestions.accdb";
        int questionNumber = 0;
        //declare Connection, command and other related objects
        OleDbConnection conGet = new OleDbConnection(cnString);
        OleDbCommand cmdGet = new OleDbCommand();
        //try
        {
            //open connection
            conGet.Open();
            cmdGet.CommandType = CommandType.Text;
            cmdGet.Connection = conGet;
            cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()"; // select all columns in all rows
            OleDbDataReader reader = cmdGet.ExecuteReader();
            reader.Read();
            String chosenAnswer = "";
            //int chosenCorrectly = 0;
            if (radioButton1.Checked)
            {
                chosenAnswer = reader["Answer 1"].ToString();
            }
            else if (radioButton2.Checked)
            {
                chosenAnswer = reader["Answer 2"].ToString();
            }
            else if (radioButton3.Checked)
            {
                chosenAnswer = reader["Answer 3"].ToString();
            }
            else
            {
                chosenAnswer = reader["Answer 4"].ToString();
            }
            if (chosenAnswer == reader["Correct Answer"].ToString())
            {
                labelQuestion.Text = table.Rows[questionNumber]["Question"].ToString();
                //and show possible answers:
                radioButton1.Text = table.Rows[questionNumber]["Answer 1"].ToString();
                radioButton2.Text = table.Rows[questionNumber]["Answer 2"].ToString();
                radioButton3.Text = table.Rows[questionNumber]["Answer 3"].ToString();
                radioButton4.Text = table.Rows[questionNumber]["Answer 4"].ToString();
                correctAnswer = table.Rows[questionNumber]["Correct Answer"].ToString();
                questionNumber++; //got to next question! 
            }
            else
            {
                MessageBox.Show("That is not the correct answer");
            }
        }
    }
}

}

我要做的是得到一个for循环它将列出数据库中的问题但同时又能让我在回答完最后一个问题后将正确回答的所有答案加起来，当然，不会得到我得到的错误