c# write database to text file

the code below output is
thisrowthisrowthisrowthisrowthisrowthisrow

How can I change it to value from database i think must correct this statement
( System.IO.File.AppendAllText(@"C:\file.txt", "thisrow");)

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 MySql.Data.MySqlClient;
using System.Web;


namespace WindowsFormsApplication1
{


   
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            string MyConString = "SERVER=localhost;" +
                "DATABASE=registration;" +
                "UID=root;" +
                "PASSWORD='';";
            MySqlConnection connection = new MySqlConnection(MyConString);
            MySqlCommand command = connection.CreateCommand();
            MySqlDataReader Reader;
            command.CommandText = "select * from teera";
            connection.Open();
            Reader = command.ExecuteReader();
            while (Reader.Read())
            {
                string thisrow = "";
                for (int i = 0; i < Reader.FieldCount; i++)
                    thisrow += Reader.GetValue(i).ToString() + ",";
                listBox1.Items.Add(thisrow);
                System.IO.File.AppendAllText(@"C:\file.txt", "thisrow");
            }
            connection.Close();

        }
    }
}

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