get the last row in a grid

smiles

Hi

I tried to update the last row in a grid but all the elements are updated

[b][size=150]void clicked()
{
 tmpaccountsum t;
    ;
     t=tmpaccountsum_ds.getFirst(1,true)?tmpaccountsum_ds.getFirst(1,true):tmpaccountsum;
    tmpaccountsum_ds.last();
    ttsbegin;
    while select forupdate t
    {
    t.Txt="12545";
    t.update();
    }
    ttscommit;
    tmpaccountsum_ds.research();
    info(t.Txt);
    super();
}[/size][/b]

Can you help please?