procedure CreateSubTree(FNodeName: string; Node: TTreeNode = nil);
var
 mLocalName: string;
 TreeNode: TTreeNode;
 Ads_Tmp: TADODataSet;
begin
 ADS_Tmp := TADODataSet.Create(Self);
 ADS_Tmp.Connection := ADOConn;
 with ADS_Tmp do
 begin
   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);
     Next;
   end;
 end;
end;

（出处：www.delphibbs.com）