protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
    {
            string sortExpression = e.SortExpression;

            if (ViewState["ifasc"].ToString() == "0")//0升序列 1降序
            {
                SortGridView(sortExpression, " ASC");
                ViewState["ifasc"] = "1";
            }
            else
            {
                SortGridView(sortExpression, " DESC");
                ViewState["ifasc"] = "0";
            }
    }
     private void SortGridView(string sortExpression, string direction)
    {
        DataTable dt = (DataTable)(ViewState["dt"]);
        DataView dv = dt.DefaultView;
        dv.Sort = sortExpression + direction;
        GridView1.DataSource = dv;
        GridView1.DataBind();
    }

------解决方案--------------------
用二楼的方法就可以

------解决方案--------------------
看三角形箭头的形状....


------解决方案--------------------
探讨

看三角形箭头的形状....