fillig cascading dropdownlist from xmlfile

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C#

Class dropdown has class titles and Name dropdown has associated names. when a class catogery is selected the associated names should be displayed in the other Namedropdown. i dont want a ajax tool kit control. and the data is in xml file. first dropdown drings the classes but i don't know how to link to second one . plea look at the code in selectIndexchanged and let me know what should i do. thisis my work assignment. the class has id like 1,2,3,4,5,6...the other xml file has names based on the id in class. i'm realating both with id.

public partial class orgList : System.Web.UI.Page 
    { 
        protected void Page_Load(object sender, EventArgs e) 
        { 
            if (!IsPostBack) 
            { 
                BindClassDropDownList(); 
            } 
 
        } 
 
 
 
        public void BindClassDropDownList() 
        { 
 
            string myXMLfile = Server.MapPath("~/OrgClasses.xml"); 
 
            DataSet CLASS_DATASET = new DataSet(); 
             
 
            try 
            { 
 
                CLASS_DATASET.ReadXml(myXMLfile); 
 
                ClassDropDownList.DataSource = CLASS_DATASET; 
 
                ClassDropDownList.DataTextField = "ClASS"; 
                 
 
 
                ClassDropDownList.DataBind(); 
                ClassDropDownList.Items.Insert(0, new ListItem("--Select--","0")); 
 
            } 
 
            catch (Exception ex) 
            { 
 
                Response.Write(ex.ToString()); 
 
            } 
 
        } 
 
 
 
        protected void ClassDropDownList_SelectedIndexChanged(object sender, EventArgs e) 
        { 
            string myXMLfile = Server.MapPath("~/OrgList.xml"); 
 
            DataSet NAME_DATASET = new DataSet(); 
            NAME_DATASET.ReadXml(myXMLfile); 
            NameDropDownList.DataSource = NAME_DATASET; 
            
            if (NameDropDownList.DataSourceID == ClassDropDownList.DataSourceID) 
            { 
                NameDropDownList.DataTextField = "NAME"; 
                NameDropDownList.DataValueField = "ID"; 
                NameDropDownList.DataBind(); 
            } 
            NameDropDownList.Items.Insert(0, new ListItem("--Select--", "0")); 
            if (ClassDropDownList.SelectedValue == "0") 
            { 
                NameDropDownList.Items.Clear(); 
                NameDropDownList.Items.Insert(0, new ListItem("--Select--", "0")); 
            } 
 
 
            } 
 
        } 
    }