protected void btnCheckOut_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            int     OrderItemID  = (int)GridView1.DataKeys[i].Value;
            Label   lblProductId = (Label)GridView1.Rows[i].FindControl("Label1");
            TextBox txtqty       = (TextBox)GridView1.Rows[i].FindControl("txtQty");
            try
            {
                string str2;
                str2 = "select * from Product_Master where Product_Id = " + lblProductId.Text;
                DataTable dt = new DataTable();
                dt = objmyclass.GetDataTable(str2);


                Int32 qty, uqty;

                qty = Convert.ToInt32(dt.Rows[0]["Quantity"].ToString());

                uqty = (Convert.ToInt32(qty) - Convert.ToInt32(txtqty.Text));

                objmyclass.con.Open();
                string str;

                str = "UPDATE Product_Master SET Quantity=" + uqty + " WHERE Product_Id=" + lblProductId.Text;
                SqlCommand cmd = new SqlCommand(str, objmyclass.con);
                cmd.ExecuteNonQuery();
                objmyclass.con.Close();
            }
            catch (Exception ex)
            {
                tran.Rollback();
            }
            finally
            {
                con.Close();
            }
        }

        // Response.Redirect("Default2.aspx");
    }