C#递归查询地区表绑定树形节点

DAL代码就不贴出来了
BLL代码：

public DataTable DiGui(int ID)
        {
            SqlParameter[] mySqlParameter =
            {
                new SqlParameter("@type",SqlDbType.NChar),
                new SqlParameter("@Parent_ID",SqlDbType.Int)
            };
            mySqlParameter[0].Value = "selectArea";
            mySqlParameter[1].Value =ID;
            return myDALMethod.QueryDataTable("selectArea", mySqlParameter);
        }

UIL代码：

public Form1()
        {
            InitializeComponent();
            delegateNewNodes delegateNewNodes = NewNodes;
            delegateNewNodes(myBLL.DiGui(0), trv_JieDian.Nodes);
        }

        BLL myBLL = new BLL();
        public delegate void delegateNewNodes(DataTable dt, TreeNodeCollection tnc);//委托
        public event delegateNewNodes eventNewNodes;

        void NewNodes(DataTable dt, TreeNodeCollection tnc)
        {
            foreach (DataRow dr in dt.Rows)
            {
                TreeNode tn = tnc.Add(dr["AREA_NAME"].ToString());
                NewNodes(myBLL.DiGui(Convert.ToInt32(dr["ID"])), tn.Nodes);
            }
        }

存储过程代码：

ALTER PROCEDURE [dbo].[selectArea]
@type varchar(200)='',		@Parent_ID int=0
AS
BEGIN
	if(@type='selectArea')
	begin
		SELECT   ID, AREA_NAME, PARENT_ID
		FROM     tbArea
		where    Parent_ID=@Parent_ID
	end
END

数据库表数据

效果：