如何在页面加载时进行排序以及如何基于GridView中的排序显示图像

我有以下代码（asp.net和背后的代码）可以实现排序：

protected void Page_Load(object sender, EventArgs e)
{

    if (!Page.IsPostBack)
    {
        PullData("", "");
        ViewState["sortOrder"] = "";
    }
}
public void PullData(string sortExp, string sortDir)
{
    DataTable taskData = new DataTable();
    string connString = @"user id = dsfsdfds;" + "password= sadasdada; server=  mg; database= ob;" /*+ "Trusted_Connection=yes;"*/  + "connection timeout=30";
    string query = @"SELECT  'http://mg/appnet/workview/objectPop.aspx?objectid=' + CAST(CT.OBJECTID AS VARCHAR) + '&classid=1224' 'Task Detail'
            ,UG.USERGROUPNAME 'Services'
            ,CT.ATTR2812 'Status'
            ,CT.ATTR2752 'Due Date'
            ,CT.ATTR2739 'Task Name'

        FROM dbo.RMOBJECTINSTANCE1224 CT
        WHERE CT.ACTIVESTATUS = 0";

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (sortExp != string.Empty)
            {
                myDataView.Sort = string.Format("{0} {1}", sortExp, sortDir);
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}

protected void yourTasksGV_Sorting(object server, GridViewSortEventArgs e)
{
    PullData(e.SortExpression, sortOrder);
}
public string sortOrder
{
    get
    {
        if (ViewState["sortOrder"].ToString() == "Desc")
        {
            ViewState["sortOrder"] = "Asc";
        }
        else
        {
            ViewState["sortOrder"] = "Desc";
        }

        return ViewState["sortOrder"].ToString();
    }
    set
    {
        ViewState["sortOrder"] = value;
    }
}

我的GridView：

<asp:GridView AlternatingRowStyle-BackColor="#E2E2E2" AutoGenerateColumns="false" OnSorting="yourTasksGV_Sorting" AllowSorting="true" ID="yourTasksGV" runat="server" ClientIDMode="Static" EmptyDataText="There is no data to display" OnRowDataBound="yourTasksGV_RowDataBound" OnRowCreated="yourTasksGV_RowCreated">
    <Columns>
        <asp:HyperLinkField Target="_blank" DataNavigateUrlFields="Task Detail" DataTextField="Task Name" DataNavigateUrlFormatString="" HeaderText="Task Details" SortExpression="Task Detail" ItemStyle-Width="35%" ItemStyle-CssClass="taskTableColumn" />
        <asp:BoundField DataField="Services" HeaderText="Services" SortExpression="Services" ItemStyle-Width="25%" ItemStyle-CssClass="taskTableColumn" />
        <asp:BoundField DataField="Status" HeaderText="Status" SortExpression="Status" ItemStyle-Width="15%" ItemStyle-CssClass="taskTableColumn" />
        <asp:BoundField DataField="Due Date" HeaderText="Due Date" SortExpression="Due Date" ItemStyle-Width="15%" ItemStyle-CssClass="taskTableColumn" />
    </Columns>
</asp:GridView>

对于第一列，我将Task Name和用作Task DetailSQL查询中列中链接的显示文本（DataTextField是“任务名称”而不是“任务详细信息”）。

如何修改我的代码以执行以下操作：

1. 当我单击Task Details选项卡时，应按进行排序，Task Name该显示为链接的显示，即Task Detail？
2. 在我要对表格进行排序的标题文本旁边显示图像？（up.png和down.png）？
3. 在页面加载时，按＃1 ASC排序并分别显示图像？

我GridView正在向用户显示的内容（请注意，链接的第一列是如何在中使用的href，显示文本是Task Name）：