递归生成树！ 有空进来看看

Question

数据库数据有240条数据，菜单深度是3级，生成树好慢，差不多要10s钟才能出现窗口看到树！，等待求解！....啥米情况？
        //递归生成树
        private void CreateNode(TreeNode tn, string parentid)
        {
            DB db = new DB();
            foreach (TreeInfo treeinfo in db.getList(parentid))
            {
                TreeNode tntemp = new TreeNode();
                tntemp.Text = treeinfo.MenuName;
                tntemp.ImageIndex = treeinfo.Icon;
                tntemp.SelectedImageIndex = treeinfo.Icon;
                string fatherMenuId = treeinfo.MenuId;
                CreateNode(tntemp, fatherMenuId);
                tn.Nodes.Add(tntemp);
            }
        }
        
        //加载窗体
        private void FrmMain_Load(object sender, EventArgs e)
        {
            treeView1.Nodes.Clear();
            TreeNode Node1 = new TreeNode("Root");
            treeView1.Nodes.Add(Node1);
            CreateNode(Node1, "10000");
        }        
        //数据库取值
         public List<TreeInfo> getList(string fatherMenuId)
        {
            List<TreeInfo> list = new List<TreeInfo>();            OleDbConnection oleDbConn = OpenConnection();            StringBuilder sb = new StringBuilder();
            if (fatherMenuId != "")
            {
                sb.Append("SELECT * FROM MenuTree WHERE FatherMenuId='" + fatherMenuId + "'");                OleDbCommand oleDbComm = new OleDbCommand(sb.ToString(), oleDbConn);
                OleDbDataReader oleDbReader = oleDbComm.ExecuteReader();                while (oleDbReader.Read())
                {
                    TreeInfo treeInfo = new TreeInfo();
                    treeInfo.MenuId = oleDbReader["MenuId"].ToString();
                    treeInfo.MenuName = oleDbReader["MenuName"].ToString();
                    treeInfo.Icon = Convert.ToInt32(oleDbReader["Icon"].ToString());
                    treeInfo.FatherMenuId = oleDbReader["FatherMenuId"].ToString();                    list.Add(treeInfo);
                }                oleDbConn.Close();
            }
            return list;
        }

Answer 1

你这么干不慢才怪，每次创建节点，都要去数据库load一下吗
foreach (TreeInfo treeinfo in db.getList(parentid))
开始load一次就够了，后面就直接使用数据集，循环里面的item

Answer 2

直接用DataTabel取出来，然后再取？

Answer 3

表结构:
CREATE TABLE MENUITEM
(
  ITEMID        VARCHAR2(100 BYTE), //ID
  TEXT          VARCHAR2(100 BYTE),//树要显示的
  PARENTITEMID  VARCHAR2(100 BYTE),//父ID同ITEMID        
  FORMNAME      VARCHAR2(100 BYTE),//窗体名
  ISMODULE      VARCHAR2(100 BYTE),//是否还有子阶
  LEVELA        VARCHAR2(100 BYTE),//没用
  IMAGENAME     VARCHAR2(100 BYTE)//没用
)生成树函数     
_datatable为SQL查询出来返回的表.   public void Load_TreeView( int ParentID, TreeNode pNode)
        {
            DataView dvTree = _datatable.DefaultView;
            //过滤ParentID,得到当前的所有子节点 
            dvTree.RowFilter = "[PARENTITEMID] = " + ParentID;
            //ArrayList Document = new ArrayList();
            foreach (DataRowView Row in dvTree)
            {
                if (pNode == null)
                {
                    TreeNode Node = _treeview.Nodes.Add(Row["TEXT"].ToString());
                    Node.Name = Row["ITEMID"].ToString();
                    Load_TreeView(Int32.Parse(Row["ITEMID"].ToString()), Node); //再次递归 
                }                else
                { //添加当前节点的子节点 
                    TreeNode Node = pNode.Nodes.Add(Row["TEXT"].ToString());
                    Node.Name = Row["ITEMID"].ToString();
                    //Document.Add(new ListViewItem(Row["TEXT"].ToString(), 1));
                    //pNode.Tag = Document;                    Load_TreeView(Int32.Parse(Row["ITEMID"].ToString()), Node); //再次递归
                }
            }
        }