TreeView 数据库

Question

 
        id      节点的index     节点名称       父节点index      父节点名称
16 0          Root                            
17 0          ZZZ        0          Root      
18 1          XXX        0          Root      
19 0          FFF        1          XXX       
20 2          VVV        0          Root      
21 3          BBB        0          Root      
22 0          FFF        3          BBB       
23 4          CCC        0          Root      
24 0          SSS        4          CCC       
25 0          DDD        0          SSS       
        private void SaveTree(TreeNode treeNode)
        {
            TreeNode parentNode = treeNode.Parent;
            string strName=this.textBox2.Text = treeNode.Text.ToString();
            string strIndex=this.textBox3.Text = treeNode.Index.ToString();
            string strParentName="";
            string strParentIndex = "";
            if (parentNode==null)
            {
                MessageBox.Show(treeNode.Text);
            }
            else
            {
                strParentName = this.textBox4.Text = parentNode.Text.ToString();
                strParentIndex=this.textBox5.Text = parentNode.Index.ToString();
            }
            string sql = "insert into tree (ownid,ownname,parentid,parentname) values ('"+strIndex+"', '"+strName+"', '"+strParentIndex+"', '"+strParentName+"')";
            cmd = new SqlCommand(sql,conn);
            cmd.ExecuteNonQuery();
            this.Update();
            Thread.Sleep(3000);
           
   
                foreach (TreeNode tn in treeNode.Nodes)
                {
                    SaveTree(tn);
                }
         }        private void Callrecursive(TreeView treeView)
        {
            TreeNodeCollection nodes = treeView.Nodes;
            foreach (TreeNode n in nodes)
            {
                SaveTree(n);
            }
        }
上面是我将一棵树存入数据库后的表，下面是代码。现在我要将表里树读出来
写不出来了。求个方法