关于树状显示(50分)

以下数据如何用树状进行显示出来？
字段1 字段2 字段3
0 A A1
1 B B1
1 C C1
2 C C2
1 D D1
2 D D2
3 D D3

大侠们，帮帮忙！

Form16.TreeView1.Items.Clear;
Form16.ADOQuery1.Close;
Form16.ADOQuery1.Sql.Clear;
Form16.ADOQuery1.Sql.Text:='select distinct 字段2 from table order by 字段1';
Form16.ADOQuery1.Open;
Form16.ADOQuery1.First;
while not Form16.ADOQuery1.Eof do
begin
//写入TreeView1根节点
Form16.TreeView1.Items.Add(nil,Form16.ADOQuery1.Fields[0].asstring);
Form16.ADOQuery1.Next;
end;
for i :=Form16.TreeView1.Items.Count-1 downto 0 do
begin
Form16.ADOQuery1.close;
Form16.ADOQuery1.SQL.Clear;
Form16.ADOQuery1.sql.text :='select 字段3 from table where 字段2='+''''+Form16.TreeView1.Items.Item.Text+'''';
Form16.ADOQuery1.Open;
Form16.ADOQuery1.First;
while not Form16.ADOQuery1.eof do begin
//写入TreeView1第二节点
Form16.TreeView1.Items.AddChild(Form16.TreeView1.Items.item,Form16.ADOQuery1.Fields[0].AsString);
Form16.TreeView1.Items.Item.ImageIndex:=1;
Form16.ADOQuery1.Next;
end;
end;
Form16.ADOQuery1.Close;