public void creattree(int fid, TreeNode parentnode)            {                DataTable dt = new DataTable();                dt = op.BindGroup();                DataRow[] drs = dt.Select("parentid=" + fid);                foreach (DataRow row in drs)                {                    if (parentnode != null)                    {                        TreeNode tempnode = new TreeNode();                        tempnode.Text = row["groupname"].ToString();                        tempnode.Name = row["groupid"].ToString();                        parentnode.Nodes.Add(tempnode);                        creattree(Convert.ToInt32(row["groupid"]), tempnode);                    }                    else                    {                        TreeNode tempnode = new TreeNode();                        tempnode.Text = row["groupname"].ToString();                        tempnode.Name = row["groupid"].ToString();                        treeView1.Nodes.Add(tempnode);                        creattree(Convert.ToInt32(row["groupid"]), tempnode);                                       }                }            }            private void bindtree()            {                treeView1.Nodes.Clear();                creattree(0,(TreeNode)null);            }

public void AddTree(int ParentID, TreeNode pNode)            {                DataTable dt = new DataTable();                dt = op.BindGroup();                DataView dvTree = new DataView(dt);                //过滤ParentID,得到当前的所有子节点                  dvTree.RowFilter = "parentid    =    " + ParentID;                foreach (DataRowView Row in dvTree)                {                    TreeNode Node = new TreeNode();                    if (pNode == null)                    {          //添加根节点                          Node.Text = Row["groupname"].ToString();                        treeView1.Nodes.Add(Node);                        //Node.Expanded = true;                        AddTree(Int32.Parse(Row["groupid"].ToString()), Node);          //再次递归                      }                    else                    {        //添加当前节点的子节点                          Node.Text = Row["groupname"].ToString();                        pNode.Nodes.Add(Node);                        //Node.Expanded = true;                        AddTree(Int32.Parse(Row["groupid"].ToString()), Node);            //再次递归                      }                }            }    private void bindtree()            {                treeView1.Nodes.Clear();                AddTree(0, (TreeNode)null);            }