ต้องการอัพเดทข้อมูลใน sql ถ้า gridview ไหนมีการ checkbox ครับ

  protected void Button1_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow grow in GridView1.Rows)
            {
                CheckBox checkboxselect = (grow.FindControl("CheckBox1") as CheckBox);
                int ID = Convert.ToInt32(grow.Cells[1].Text);              
                updaterow(ID, Label1.Text);
             
               bindgrid();
            }          
        }
         private void updaterow(int ID, String markstatus)
            {

             string mycon = "Data Source = WAKDATABASE; Initial Catalog = OT; Persist Security Info=True;user ID = sa; password=P@ssw0rd";
             string updatedata = "update Detail set mg='" + Label1.Text + "' where ID=" + ID;
             SqlConnection con = new SqlConnection (mycon);           
        
            if (con.State == ConnectionState.Closed)
                con.Open();

            cmd.CommandText = updatedata;
            cmd.Connection =con;           
            cmd.ExecuteNonQuery();
            con.Close();
            bindgrid();
        }