C# 树状图

效果图：

结构：

frmMain层

using hierarchy.BLL;
using hierarchy.Model;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace hierarchy.UI
{
    public partial class frmMain : Form
    {
        public frmMain()
        {
            InitializeComponent();
        }
        hierarchysBll bll = new hierarchysBll();
        List<Thelog> list = null;
        private void frmMain_Load(object sender, EventArgs e)
        {
            tvmo();
        }

        #region MyRegion



        public void tvmo() {
            tvMov.Nodes.Clear();
            TreeNode dd = null;
            list = bll.findAll();
            foreach (Thelog item in list)
            {
                dd = new TreeNode();
                if (item.Qfatherid == 0)
                {
                    dd.Tag = item.Qid;
                    dd.Text = item.Qname;
                    tvMov.Nodes.Add(dd);
                    GetNode(dd, item.Qid);
                }
            }

        }



        private void GetNode(TreeNode Qname, int Qid)
        {
            list = bll.findAll();
            TreeNode tn = null;
            if (list.Count > 0)
            {
                foreach (Thelog drv in list)
                {
                    if (Qid == drv.Qfatherid)
                    {
                        tn = new TreeNode();
                        tn.Tag = drv.Qid;
                        tn.Text = drv.Qname;
                        Qname.Nodes.Add(tn);
                        GetNode(tn, drv.Qid);
                    }

                }
            }
        }

        #endregion

        private void button1_Click(object sender, EventArgs e)
        {
            TreeNode node = tvMov.SelectedNode;
            int s = (int)node.Tag;
            int i = node.Level;
            frmaddlei add = new frmaddlei(s, i, node);
            add.Show();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            TreeNode node = tvMov.SelectedNode;
            int id = (int)node.Tag;

            bool bl = bll.finddel(id);
            if (bl)
            {
                node.Remove();
                MessageBox.Show("删除成功！！");
            }
            else
            {
                MessageBox.Show("出错啦！！！");
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            TreeNode node = tvMov.SelectedNode;
            int s = (int)node.Tag;
            string i = node.Text;
            frmup add = new frmup(s, i, node);
            add.Show();
        }

        private void tvMov_AfterSelect(object sender, TreeViewEventArgs e)
        {
            TreeNode node = tvMov.SelectedNode;
            string i = node.Text;

            MessageBox.Show(i);
        }



    }
}

 删除层

using hierarchy.BLL;
using hierarchy.Model;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace hierarchy.UI
{
    public partial class frmaddlei : Form
    {
        public frmaddlei()
        {
            InitializeComponent();
        }
        int ss = 0;
        int ii = 0;
        TreeNode aodee = null;
        public frmaddlei(int s, int i, TreeNode aode)
        {
            ss = s;
            ii = i;
            aodee = aode;
            InitializeComponent();

        }
        hierarchysBll bll = new hierarchysBll();
        private void button1_Click(object sender, EventArgs e)
        {
            Thelog Thelog = new Thelog();
            Thelog.Qname = tbxname.Text;
            Thelog.Qfatherid=ii;
            Thelog.Qtier = ss;
            bool bl = bll.findAdd(Thelog);
            if (bl)
            {
                MessageBox.Show("添加成功");
                string guid = Guid.NewGuid().ToString();
                TreeNode t = new TreeNode(this.tbxname.Text);
                t.Tag = guid;
                aodee.Nodes.Add(t);
                this.Close();

            }
        }
    }
}

 Dal层

using hierarchy.Model;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace hierarchy.DAL
{
    public class hierarchysDAL
    {

        //01.写一个查询所有年级的方法
        public List<Models> findAllGrades()
        {
            List<Models> list = new List<Models>();
            string sql = "select [StudentName] from [Address_IS]";
            DataTable table = SQLHelper.ExecuteDataTable(sql);
            foreach (DataRow item in table.Rows)
            {
                Models Models = new Models();
                Models.StudentName = item["StudentName"].ToString();
                list.Add(Models);
            }
            return list;



        }

        //01.写一个查询所有年级的方法
        public List<Thelog> findAll()
        {
            List<Thelog> list = new List<Thelog>();
            string sql = "SELECT * FROM Thelog";
            DataTable table = SQLHelper.ExecuteDataTable(sql);
            foreach (DataRow item in table.Rows)
            {
                Thelog Thelog = new Thelog();
                Thelog.Qid = Convert.ToInt32(item["qid"]);
                Thelog.Qname = item["qname"].ToString();
                Thelog.Qtier = Convert.ToInt32(item["qtier"]);
                Thelog.Qfatherid = Convert.ToInt32(item["qfatherid"]);
                list.Add(Thelog);
            }
            return list;

        }

        
        public bool findAdd(Thelog Thelog)
        {
            bool bl = false;
            string sql = @"INSERT INTO Thelog(qname,qfatherid,qtier) VALUES(@name,@fatherid,@tid)";
            SqlParameter[] paras = {
                                      new SqlParameter("@name",  Thelog.Qname),
                                      new SqlParameter("@fatherid", Thelog.Qtier),
                                      new SqlParameter("@tid",   Thelog.Qfatherid)
                                       };
            int i = (int)SQLHelper.ExecuteNonQuery(sql,paras);
            if (i > 0)
            {
                bl = true;
            }
            return bl;

        }

        public bool finddel(int id) {
            bool bl = false;
            string sql = "delete from Thelog where qid=@nid";
            SqlParameter[] paras = {
                                       new SqlParameter("@nid",id)
                                   };
            int i = (int)SQLHelper.ExecuteNonQuery(sql, paras);
            if (i > 0)
            {
                bl = true;
            }
            return bl;
        }

        public bool update(Thelog Thelog)
        {
            bool bl = false;
            string sql = "update Thelog set qname=@name where qid=@id";
            SqlParameter[] paras = {
                                    new SqlParameter("@name",  Thelog.Qname),
                                      new SqlParameter("@id", Thelog.Qid)
                                   };
            int i = (int)SQLHelper.ExecuteNonQuery(sql, paras);
            if (i > 0)
            {
                bl = true;
            }
            return bl;
        }


    }
}