procedure TForm1.FormCreate(Sender: TObject);
begin
ComboBox1.Items.Clear;
  with ADOQuery1 do
   begin
     Close;
     SQL.Clear;
     SQL.Add('select * from yxdmb order by yxdm');
     Open;

     try
         First;
         while not EOF do
          begin
           ComboBox1.Items.Add(Fields[1].Asstring);
           Next;
          end;
        finally
         EnableControls;
        end;//End try
   end;  // ADOQuery1
  ComboBox1.ItemIndex := 0;
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
var n:integer;
    str1:string;
begin
  n := ComboBox1.ItemIndex;
  with ADOQuery1 do
   begin
    First;
    MoveBy(n);
   end;
   str1:=ADOQuery1.Fields[0].AsString;
  with ADOQuery2 do
   begin
     Close;
     SQL.Clear;
     SQL.Add('select * from xsjbxxb where yxdm='''+str1+'''');
     Open;
   end;
end;

end.

谢谢！！！