Copy data from one field to another field in table for selected lines while button clicked in form in AX2012

Copy data from one field to another field in table for selected lines while button clicked in form in AX2012 :

Example Code:

void clicked()
{
    PMSubJobLotLevelLines   tPMSubJobLotLevelLines;
    tPMSubJobLotLevelLines = PMSubJobLotLevelLines_ds.getFirst();
    while (tPMSubJobLotLevelLines)
    {
        if (tPMSubJobLotLevelLines.Selected == NoYes::Yes)
        {
           
            ttsBegin;
            tPMSubJobLotLevelLines.Additional4 = tPMSubJobLotLevelLines.EquipmentNumber;
            tPMSubJobLotLevelLines.update();
            ttsCommit;
        }
            tPMSubJobLotLevelLines = PMSubJobLotLevelLines_ds.getNext();

    }
    super();

}