如何使用wir循环而不是开关案例语句以允许有多个问题数

Question

我目前正在努力在C＃开发“测验”程序，我想提出的问题数量，以便将来可以轻松地更改它。以前，我使用了一个开关案例语句来运行一系列20个问题，并且每个语句中的代码几乎相同，除了我从mySQL中提取的值的参数。但是，当我尝试在一段时间内做同样的事情时，测验窗口不会弹出。这是在Visual Studio 2019上使用Web测验.NET模板构建的。请看一下屏幕截图，让我知道您是否看到可能导致测验不会在While循环中显示的任何错误，但确实显示在开关情况下。 screenShot 另外，此外，这是当我使用开关情况时会弹出的内容，但没有与while循环。我的代码：

 private void askQuestion(int qnum)
    {
        int numOfRows = 20;
        int questionNum = qnum;
        while (questionNum <= numOfRows)
        {
            string num = "'" + qnum.ToString() + "'";
            lblQuestion.Text = getValue("question", "quizquestions", "questionid", num, "questionid", num);
            //lblQuestion.Text = "An alarm may be canceled by calling the monitoring station and giving them the correct passcode and / or password.";

            button1.Text = getValue("answertext", "answertable", "answerid", "'1'", "questionid", num);
            button2.Text = getValue("answertext", "answertable", "answerid", "'2'", "questionid", num);
            button3.Text = getValue("answertext", "answertable", "answerid", "'3'", "questionid", num); ;
            button4.Text = getValue("answertext", "answertable", "answerid", "'4'", "questionid", num); ;

            scoreBox.Text = "Current Score: " + score + "/20";
            currentQ.Text = "Current Question: " + questionNumber;

            correctAnswer = Int32.Parse(getValue("correctid", "quizanswers", "questionid", num, "questionid", num));

            questionNum++;
        }
    }
    
    /*private void askQuestion(int qnum)
    {
        
        switch (qnum)
        {
            case 1:
                //pictureBox1.Image = Properties.Resources.questions;


                lblQuestion.Text = getValue("question", "quizquestions", "questionid", "'1'", "questionid", "1");
                //lblQuestion.Text = "An alarm may be canceled by calling the monitoring station and giving them the correct passcode and / or password.";

                button1.Text = getValue("answertext", "answertable", "answerid", "'1'", "questionid", "'1'");
                button2.Text = getValue("answertext", "answertable", "answerid", "'2'", "questionid", "'1'");
                button3.Visible = false;
                button3.Text = "";
                button4.Visible = false;
                button4.Text = "";

                scoreBox.Text = "Current Score: " + score +"/20";
                currentQ.Text = "Current Question: " + questionNumber;

                correctAnswer = Int32.Parse(getValue("correctid", "quizanswers", "questionid", "'1'", "questionid", "'1'")); 

                break;
            case 2:...

Answer 1

public string getValue(string columnName, string tableName, string refName, string refValue, string ref2Name, string ref2Value)
    {
        string serverIp = "localhost";
        string username = "root";
        string password = "Shared1203";
        string databaseName = "faquiz";

        string value = "";

        string dbConnectionString = string.Format("server={0};uid={1};pwd={2};database={3};", serverIp, username, password, databaseName);
        string query = "SELECT " + columnName + " FROM " + tableName + " WHERE " + refName + " = " + refValue + " AND " + ref2Name + " = " + ref2Value;

        var conn = new MySql.Data.MySqlClient.MySqlConnection(dbConnectionString);
        conn.Open();

        var cmd = new MySql.Data.MySqlClient.MySqlCommand(query, conn);
        var reader = cmd.ExecuteReader();

        while (reader.Read())
        {
            var someValue = reader[columnName];

            value = someValue.ToString();
        }

        return value;
    }

没有收到错误