protected void gridview_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        grd_completed_order.PageIndex = e.NewPageIndex;
        DataTable dt = Select_Logic.completed_orders();

        grd_completed_order.DataSource = dt;
        grd_completed_order.DataBind();
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["username"] == "")
        {
            Response.Redirect("LoginPage.aspx");
        }


        DataTable dt = Select_Logic.completed_orders();

        grd_completed_order.DataSource = dt;
        grd_completed_order.DataBind();
    }