ช่วยดูให้หน่อยนะค่ะ ขอบคุนมากก
พยายามแก้แล้ว แต่ยังทำไม่ได้

public partial class test_Product : System.Web.UI.Page
    {
        private MySqlConnection con = new MySqlConnection("SERVER=localhost;" + "DATABASE=shop;" + "UID=root;" + "PASSWORD=1234;");

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindEmployeeDetails();
            }
        }

        protected void BindEmployeeDetails()
        {
            try
            {
                con.Open();
                MySqlCommand cmd = new MySqlCommand("Select * from product", con);
                MySqlDataAdapter da = new MySqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                con.Close();
                if (ds.Tables[0].Rows.Count > 0)
                {
                    gvDetails.DataSource = ds;
                    gvDetails.DataBind();
                }
                else
                {
                    ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
                    gvDetails.DataSource = ds;
                    gvDetails.DataBind();
                    int columncount = gvDetails.Rows[0].Cells.Count;
                    gvDetails.Rows[0].Cells.Clear();
                    gvDetails.Rows[0].Cells.Add(new TableCell());
                    gvDetails.Rows[0].Cells[0].ColumnSpan = columncount;
                    gvDetails.Rows[0].Cells[0].Text = "No Records Found";
                }
            }
            catch (Exception ex)
            {
                Label2.Text = ex.ToString();
            }
        }

protected void gvDetails_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            if (e.CommandName == "Add")
            {
                GridViewRow Row = ((GridViewRow)((Control)sender).Parent.Parent);
                string strProductID = e.CommandArgument.ToString();
                DataTable dt = null;
                DataRow dr = null;

                if ((Session["myCart"] == null))
                {
                    dt = new DataTable();
                    dt.Columns.Add("ProdID");
                    dt.Columns.Add("Qty");
                    Session["myCart"] = dt;
                }

                dt = (DataTable)Session["myCart"];
                DataRow[] foundRows = null;
                foundRows = dt.Select("ProdID = '" + strProductID + "'");
                if (foundRows.Length == 0)
                {
                    dr = dt.NewRow();
                    dr["ProdID"] = strProductID;
                    dr["Qty"] = 1;
                    dt.Rows.Add(dr);
                }
                else
                {
                    DataRow[] updateRow = null;
                    updateRow = dt.Select("ProdID = '" + strProductID + "'");
                    updateRow[0]["Qty"] = Convert.ToInt32(updateRow[0]["Qty"]) + 1;
                }

                Session["myCart"] = dt;
                Response.Redirect("Home.aspx");
            }
        }
}