unit1.pas

用数据库实现的树形结构

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, StdCtrls, ComCtrls, Grids, DBGrids;

type
  TForm1 = class(TForm)
    ADOConnection1: TADOConnection;
    Button1: TButton;
    ADOQuery1: TADOQuery;
    Button2: TButton;
    PageControl1: TPageControl;
    TabSheet1: TTabSheet;
    TreeView1: TTreeView;
    TabSheet2: TTabSheet;
    DataSource1: TDataSource;
    ADOQuery1ID: TAutoIncField;
    ADOQuery1ParentID: TIntegerField;
    ADOQuery1Name: TWideStringField;
    DBGrid1: TDBGrid;
    Memo1: TMemo;
    procedure Button2Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure FillTreeView(TreeView: TTreeView);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button2Click(Sender: TObject);
begin
  Close;
end;

procedure TForm1.FillTreeView(TreeView: TTreeView);
  procedure CreateSubTree(FNodeName: string; Node: TTreeNode = nil);
  var
    mLocalName: string;
    TreeNode: TTreeNode;
    Ads_Tmp: TADODataSet;
  begin
    ADS_Tmp := TADODataSet.Create(Self);
    ADS_Tmp.Connection := ADOConnection1;
    with ADS_Tmp do
    try
      Close;
      CommandText := 'Select * from Type Where ParentID =' + FNodeName;
      Open;
      First;
      while not Eof do
      begin
        mLocalName := FieldbyName('ID').Asstring;
        TreeNode := TreeView.Items.AddChild(Node, FieldByName('Name').AsString);
        CreateSubTree(mLocalName, TreeNode); // 此处循环递归
        Next;
      end;
    finally
      ADS_Tmp.Free;
    end;
  end;
begin
  TreeView.Items.BeginUpdate;
  TreeView.Items.Clear;
  with TreeView.Items.Add(nil, '所有目录') do
  begin
    ImageIndex := 1;
    SelectedIndex := 1;
  end;
  CreateSubTree('0', TreeView.Items[0]);
  TreeView.Items.EndUpdate;
  TreeView.Items[1].Selected := True;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  FillTreeView(TreeView1);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  ADOQuery1.Close;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ADOQuery1.Open;
end;

end.