<asp:TreeView ID="tree" runat="server" ForeColor="black" RootNodeStyle-ImageUrl="~/xpMyComp.gif" LeafNodeStyle-ImageUrl="~/help_page.gif"> </asp:TreeView>

C# Code

public void GenrateTreeView()

{

    DataSet myDataSet = GetData();

    foreach (DataRow parentRow in myDataSet.Tables["department"].Rows)

    {

        TreeNode parentNode = new TreeNode((string)parentRow["dname"]);

        tree.Nodes.Add(parentNode);

        foreach (DataRow childRow in parentRow.GetChildRows("Child"))

        {

            TreeNode childNode = new TreeNode((string)childRow["ename"]);

            parentNode.ChildNodes.Add(childNode);

        }

    }

}

public DataSet GetData()

{

    string strcon = System.Configuration.ConfigurationManager.AppSettings.Get("constring");

    string empQuery = "SELECT * FROM employee ";

    string deptQuery = "SELECT * FROM department";

    SqlConnection con = new SqlConnection();

    SqlDataAdapter da = new SqlDataAdapter(empQuery, strcon);

    SqlDataAdapter da1 = new SqlDataAdapter(deptQuery, strcon);

    DataSet myDataSet = new DataSet();

    da.Fill(myDataSet, "employee");

    da1.Fill(myDataSet, "department");

    myDataSet.Relations.Add("Child", myDataSet.Tables["department"].Columns["deptno"],

    myDataSet.Tables["employee"].Columns["deptno"]);

    return myDataSet;