ASP.NET中GridView正反双向排序

效果图：点姓名各2次的排序，点其他也一样可以。


后台代码：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class Default3 : System.Web.UI.Page
{

//清清月儿的博客http://blog.csdn.net/21aspnet
    SqlConnection sqlcon;
    string strCon = "Data Source=(local);Database=北风贸易;Uid=sa;Pwd=";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ViewState["SortOrder"] = "身份证号码";
            ViewState["OrderDire"] = "ASC";
            bind();
        }
    }
    protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
    {
        string sPage = e.SortExpression;
        if (ViewState["SortOrder"].ToString() == sPage)
        {
            if (ViewState["OrderDire"].ToString() == "Desc")
                ViewState["OrderDire"] = "ASC";
            else
                ViewState["OrderDire"] = "Desc";
        }
        else
        {
            ViewState["SortOrder"] = e.SortExpression;
        }
        bind();
    }

    public void bind()
    {
       
        string sqlstr = "select top 5 * from 飞狐工作室";
        sqlcon = new SqlConnection(strCon);
        SqlDataAdapter myda = new SqlDataAdapter(sqlstr, sqlcon);
        DataSet myds = new DataSet();
        sqlcon.Open();
        myda.Fill(myds, "飞狐工作室");
        DataView view = myds.Tables["飞狐工作室"].DefaultView;
        string sort = (string)ViewState["SortOrder"] + " " + (string)ViewState["OrderDire"];
        view.Sort = sort;
        GridView1.DataSource = view;
        GridView1.DataBind();
        sqlcon.Close();
    }
}

前台主要代码：
<asp:GridView ID="GridView1" runat="server" AllowSorting="True" AutoGenerateColumns="False"
                        CellPadding="3" Font-Size="9pt" OnSorting="GridView1_Sorting" BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px">
                        <FooterStyle BackColor="White" ForeColor="#000066" />
                        <Columns>
                             <asp:BoundField DataField="身份证号码" HeaderText="用户ID" SortExpression="身份证号码" />
                            <asp:BoundField DataField="姓名" HeaderText="用户姓名