访问数据表、数据表的字段、数据表的数据行

从数据库里读取用户指定的某一个值
效果图：

public DataTable dt;

    protected void Page_Load(object sender, EventArgs e)

    {

        string s;

        OleDbConnection conn = new OleDbConnection();

        conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("DB.mdb");

        OleDbDataAdapter ad = new OleDbDataAdapter("select * from stu", conn);

        DataSet ds = new DataSet();

        ad.Fill(ds, "stu");

        dt = ds.Tables["stu"];

 

        if (!IsPostBack)

        {

            for (int i = 0; i < dt.Rows.Count; i++)

                DropDownList1.Items.Add("第" + (i + 1) + "行");

            for (int j = 0; j < dt.Columns.Count; j++)

                DropDownList2.Items.Add(dt.Columns[j].Caption);

        }

    }      

   

    protected void Button1_Click(object sender, EventArgs e)

    {    

        Label1.Text = DropDownList1.SelectedItem + "," + DropDownList2.SelectedItem + "字段的值为["

            + dt.Rows[DropDownList1.SelectedIndex].ItemArray[DropDownList2.SelectedIndex]+"]";

    }

但是有一个问题，如何原样输入“<”和“>”这样的html标记符？