Updating attendance for students in school project

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;

public partial class Faculty_attendance : System.Web.UI.Page
{
    SqlConnection cn = new SqlConnection("Data Source=DESKTOP-UIGAOQI\\SQLEXPRESS;Initial Catalog=mydb;Integrated Security=True;");
    protected void Page_Load(object sender, EventArgs e)
    {
        Label3.Text = "Mark Attendance for " + DateTime.Now.ToShortDateString();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {

    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        foreach (GridViewRow row in GridView1.Rows)
        {
            String RegNo = row.Cells[0].Text;
            String Name = row.Cells[1].Text;
            RadioButton rbtn1 = (row.Cells[2].FindControl("RadioButton1") as RadioButton);
            RadioButton rbtn2 = (row.Cells[2].FindControl("RadioButton2") as RadioButton);
            String status1;
            if (rbtn1.Checked)
            {
                status1 = "Present";
            }
            else
            {
                status1 = "Absent";
            }
            String dateofclass1 = Label3.Text;
            String sclass1 = DropDownList1.SelectedItem.Text;
            saveattendance(RegNo, Name, dateofclass1, status1, sclass1);
        }
        Label4.Text = "Attendance has been saved succesfully";
    }

    private void saveattendance(String regno, String studentname, String dateofclass1, String status, String sclass)
    {
        try
        {
            String query = "insert into attendance(RegNo,Name, Date,Status,Class) values(" + regno + ",'" + studentname + "' '" + dateofclass1 + "','" + status + "','" + sclass + "')";
            String mycon = "Data Source=DESKTOP-UIGAOQI\\SQLEXPRESS;Initial Catalog=mydb;Integrated Security=True";
            SqlConnection cn = new SqlConnection(mycon);
            cn.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = query;
            cmd.Connection = cn;
            cmd.ExecuteNonQuery();
        }
        catch (SqlException)
        {
        }
    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
       
    }
    protected void DropDownList1_SelectedIndexChanged1(object sender, EventArgs e)
    {

    }
}