How to save checked row value of grid view in database using C# ASP.NET?

protected void btnSave_Click(object sender, EventArgs e)
        {
            int id = 0;
            string strname = string.Empty;
            int Phone_Number = 0;
            string Address = string.Empty;
            for (int i = 0; i <grd_Data.Rows.Count; i++)
            {
                CheckBox chk = (CheckBox)grd_Data.Rows[i].Cells[1].FindControl("chkSelecct");
                if (chk.Checked)
                {
                  //  id = Convert.ToInt32(grd_Data.Rows[i].Cells[1].Text);
                    strname = grd_Data.Rows[i].Cells[1].Text;
                 //   Phone_Number = Convert.ToInt32(grd_Data.Rows[i].Cells[3].ToString());
                    Address = grd_Data.Rows[i].Cells[3].Text.ToString();

                    SqlConnection con = new SqlConnection(CS);
                    con.Open();
                    string insertquery="insert into tblCheck(name,phone,address) values(@name,@phone,@address)";
                    SqlCommand cmd = new SqlCommand(insertquery,con);
                    cmd.Parameters.AddWithValue("@name", strname);
                    cmd.Parameters.AddWithValue("@phone", Phone_Number);
                    cmd.Parameters.AddWithValue("@address", Address);
                    cmd.ExecuteNonQuery();
                    con.Close();
                    
                }
            }