Populate TreeView using entity framework 4

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C#3.0

C#

entity-framework

Hi i have the following codes running in my project. What i want to know from you guys is that how do i write the same code in EF 4 to populate a treeView. I have one table named "tPatients" from where i am displaying all patient names datewise. i.e.

18-June-2013
--Mr. A
--Mr. B
19-June-2013
--Mr. C
--Mr. D
--Mr. E
20-June-2013
--Mr. F
--Mr. G



Hope you guys help me. Thanking you.

private void PopulateTreeView()
    {
        treePatient.Nodes.Clear();

        SqlDataAdapter daPatient = new SqlDataAdapter("SELECT TOP 100 PERCENT pId, pBillDate, pName FROM tPatients WHERE pBillDate >= DATEADD(day,-7, GETDATE())", con);
        SqlDataAdapter daDate = new SqlDataAdapter("SELECT * FROM viewGroupDate", con);

        DataSet ds = new DataSet();
        daPatient.Fill(ds, "tPatients");
        daDate.Fill(ds, "viewGroupDate");

        //Add root node
        TreeNode root = new TreeNode("Patients");
        root.Tag =0;
        root.Expand();

            ds.Relations.Add("Dept_SubDept", ds.Tables["viewGroupDate"].Columns["pBillDate"], ds.Tables["tPatients"].Columns["pBillDate"]);
            foreach (DataRow dr in ds.Tables["viewGroupDate"].Rows)
            {

                DateTime dt = Convert.ToDateTime(dr["pBillDate"]);
                TreeNode tn = new TreeNode(String.Format("{0:dd-MMM-yyyy}", dt));
                tn.Tag = 0;

                foreach (DataRow drChild in dr.GetChildRows("Dept_SubDept"))
                {

                    TreeNode childTn = new TreeNode(drChild["pId"].ToString() + "- " + drChild["pName"].ToString());
                    childTn.Tag = drChild["pId"];

                    tn.Nodes.Add(childTn);

                }

                root.Nodes.Add(tn);

            }
            treePatient.BeginUpdate();
            treePatient.Nodes.Add(root);  
            treePatient.EndUpdate();

    }