DAL
public List<TreeModel> GetAllTree()
        {
            string sql = "select * from T_department";
            List<TreeModel> list = new List<TreeModel>();
            DataTable dt = SqlHelper.ExecuteDataTable(sql);
            foreach (DataRow dr in dt.Rows)
            {
                TreeModel tm = RowToModel(dr);
                list.Add(tm);
            }
            return list;
        }
        private TreeModel RowToModel(DataRow dr)
        {
            TreeModel tm = new TreeModel();
            tm.D_Cid = dr["d_cid"].ToString();
            tm.D_Id = dr["d_id"].ToString();
            tm.D_Name = dr["d_name"].ToString();
            tm.D_Pid = dr["d_pid"].ToString();
            return tm;
        }
BLL
public class TreeBLL
    {
        TreeDAL dal = new TreeDAL();
        public List<TreeModel> GetAllTree()
        {
            return dal.GetAllTree();
        }
    }
UI中返回List<TreeModel>,请大神帮忙写下UI  谢谢
表是这么设计的
A    总经办            1    0
AA    生产部            11    1
AAA    保修部            111    11
BAA    非保部            211    11
BA    物流部            21    1
ABA    物流一部    121    21
BBA    物流二部    221    21
CBA    物流三部    321    21
CA    市场部            31    1
ACA    市场拓展    131    31
BCA    营销部            231    31
ABCA    电器营销部    1231    231
BBCA    电子营销部    2231    231