delphi怎样实现单击treeview中的父节点，显示相应的子节点
delphi怎样实现单击treeview中的父节点，显示相应的子节点
求高手！！！！

[解决办法]
procedure TForm1.maketree;
var
Node : TTreeNode;

begin
with ADOQuery1 do
begin
Close;
sql.Clear;
sql.Add('select func_name,id from ok_function where parent_id=0');
Open;
end;
while not ADOQuery1.Eof do
begin
Node :=Tree.Items.Add(nil,ADOQuery1.FieldByName('func_name').AsString);
gridqry.Close;
gridqry.SQL.Clear;
gridqry.SQL.Add('select func_name from ok_function where parent_id='''+ADOQuery1.FieldByName('id').AsString+'''');
gridqry.Open;
while not gridqry.Eof do
begin
Tree.Items.Addchild(node,gridqry.FieldByName('func_name').AsString);
gridqry.Next;
end;
gridqry.Close;
ADOQuery1.Next;
end;
ADOQuery1.Close;
end;