PO List Confirmed more then one with comparison

static void JobMatchData(Args _args)
{
         PurchTable purchTable;
         PurchTableHistory PurchTableHistory;
         PurchLine purchline;
         PurchLineHistory purchLineHistory;


          int      a, k;


          a = 0;

    while select purchTable join PurchTableHistory where purchTable.PurchId == PurchTableHistory.PurchId
    {
      while select purchline where PurchLine.PurchId == purchTable.PurchId
       {
        if(a == 0)
           {
             info(strFmt("purchid --%1",purchtable.PurchId));

             a = 1;
           }
         info(strFmt(" item =%1",PurchLine.ItemId));

        }
        while select purchLineHistory where purchLineHistory.PurchId == purchTable.PurchId
       {
        if(a == 0)
           {
             //info(strFmt("purchid --%1",purchtable.PurchId));

             a = 1;
           }
         info(strFmt(" item =%1",purchLineHistory.ItemId));

        }

    a =0;

    }


}