c# treeview 基本知识

  private void Form1_Load(object sender, EventArgs e)
         {
             BindTreeView();
             treeView1.Focus();
             treeView1.GotFocus += treeView1_GotFocus;

         }

         void treeView1_GotFocus(object sender, EventArgs e)
         {
             textBox1.Text = "北京市";

         }

         private void BindTreeView()
         {
             string mysql = "select * from provincial ";
             DataTable dt = new DataTable();
             dt = MySqlHelp.GetDataTable(mysql);
             //定义临时树节点
             TreeNode tmpNd;
             foreach (DataRow row in dt.Rows)
             {
                 tmpNd =new TreeNode();
                 tmpNd.Text=row["provincialName"].ToString();
                 treeView1.Nodes.Add(tmpNd);
                 InitTreeView(tmpNd.Nodes, row["provincialID"].ToString());
             }

         }

         private void InitTreeView(TreeNodeCollection treeNodeCollection, string id)
         {
             TreeNode tmpNd;
             string sql = string.Format("select * from city where provincialID={0}", id);
             DataTable dt = new DataTable();
             dt= MySqlHelp.GetDataTable(sql);
             foreach (DataRow row in dt.Rows)
             {
                 tmpNd = new TreeNode();
                 tmpNd.Text=row["cityName"].ToString();
                 treeNodeCollection.Add(tmpNd);

             }
         }

         private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
         {
             if (e.Node.Parent == null)
             {
                 textBox1.Text = e.Node.Nodes[].Text;
             }
             else
             {
                 textBox1.Text = e.Node.Text;
             }

         }
     }