幻想曲.Net

今天看到有朋友在留本中问到:.net的无限级分类怎么写法
其实所有的无限级基本上都是要用递归去计算的
做了一个Demo来演示
利用.net 2.0中的TreeView控件与数据库绑定，生成无限级的树目录
数据表的结构


rootid与id就会形成一种父子关系

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page
{
    protected string _connstr = ConfigurationManager.ConnectionStrings["DemoConnectionstrings"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            BindTree();
            using (SqlConnection _conn = new SqlConnection(_connstr))
            {
                SqlCommand _comm = new SqlCommand("select * from treeview", _conn);

                _conn.Open();
                using (SqlDataReader r = _comm.ExecuteReader())
                {
                    while (r.Read())
                    {
                        ListItem item = new ListItem(r["txt"].ToString(), r["id"].ToString());
                        this._dd_parent.Items.Add(item);
                    }
                }
            }
            this._dd_parent.Items.Insert(0, new ListItem(".......", "0"));
        }
    }
    protected void BindTree()
    {
        TreeNode node = new TreeNode();   //这里是创建一个根节点,就是dome中看到的Root
        node.Text = "Root";
        CreateChildTree(node, 0);   
        _tree_view.Nodes.Add(node);
    }

    protected void CreateChildTree(TreeNode _parentNode, int _parentID)
    {
        using (SqlConnection _conn = new SqlConnection(_connstr))
        {
            SqlCommand _comm = new SqlCommand();
            string sql = "select * from treeview where rootid=@rootid";
            _comm.Parameters.Add("@rootid", SqlDbType.Int).Value = _parentID;
            _comm.CommandText = sql;
            _comm.Connection = _conn;
            _conn.Open();
            using (SqlDataReader r = _comm.ExecuteReader())
            {
                while (r.Read())
                {
                    TreeNode _node = new TreeNode(r["txt"].ToString());
                        CreateChildTree(_node, (int)r["ID"]);  //递归出子节点
                        _parentNode.ChildNodes.Add(_node);
                }
            }
        }
    }
    protected void _btn_submit_Click(object sender, EventArgs e)
    {
        int _rootid = Convert.ToInt16(this._dd_parent.SelectedValue);
        string _txt = this._txt_txt.Text.Trim();
        using (SqlConnection _conn = new SqlConnection(_connstr))
        {
            SqlCommand _comm = new SqlCommand("insert into treeview (txt,rootid) values (@txt,@id)", _conn);
            _comm.Parameters.Add("@txt", SqlDbType.VarChar, 50).Value = _txt;
            _comm.Parameters.Add("@id", SqlDbType.Int).Value = _rootid;
            _conn.Open();
            _comm.ExecuteNonQuery();
        }
        this._tree_view.Nodes.Clear();
        BindTree();
    }
}