Exporting Data from Database To Text File in C#

public override void VerifyRenderingInServerForm(Control control)
    {
    }
    protected void btnExport_Click(object sender, System.EventArgs e)
    {
        string connectionString = WebConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            try
            {
                connection.Open();
            }
            catch (System.Data.SqlClient.SqlException ex)
            {
                // handle
                return;
            }
            string selectCommandText = "SELECT * FROM Students";
            using (SqlDataAdapter adapter = new SqlDataAdapter(selectCommandText, connection))
            {
                using (DataTable table = new DataTable("Students"))
                {
                    adapter.Fill(table);
                    StringBuilder commaDelimitedText = new StringBuilder();
                    //commaDelimitedText.AppendLine("col1,col2,col3"); // optional if you want column names in first row
                    foreach (DataRow row in table.Rows)
                    {
                        string value = string.Format("{0} {1} {2}  {3}  {4}  {5}", row[0], row[1], row[2], row[3], row[4], row[5]); // how you format is up to you (spaces, tabs, delimiter, etc)
                        commaDelimitedText.AppendLine(value);
                    }
                    string str = "CustomName1";
                    string btr = "CustomName2";
                    File.WriteAllText(@"C:\\temp\" + str + btr + ".txt", commaDelimitedText.ToString());
                }
            }
        }
    }