DataTable Dt_RoomMaster = new DataTable();

            Dt_RoomMaster = Sp_Connection.fetchdatatable("select * from table");



            treeview.Nodes.Clear();



    foreach (DataRow dr in Dt_RoomMaster.Rows)

             {

                TreeNode trParent = new TreeNode();

                trParent.Text = dr["ColumnName"].ToString();

                trParent.Expand();

                treeview.Nodes.Add(trParent);

             }