[dech]

Попробуйте такой запрос (я тут правда успел убрать те 2 таблицы, которые посчитал ненужными):

select ITEMID from VENDSPLISTTRANS
    group by ITEMID

join VENDSPLISTJOUR
    where VENDSPLISTTRANS.INTERNALSP == VENDSPLISTJOUR.INTERNALSP 
      and VENDSPLISTJOUR.SPDATE >= 25\09\2013
      and VENDSPLISTJOUR.SPDATE <  02\10\2013

outer join PURCHID, INVOICEDATE from VENDINVOICETRANS
    where VENDSPLISTTRANS.INTERNALSP == VENDINVOICETRANS.INTERNALSP
      and VENDSPLISTTRANS.ITEMID == VENDINVOICETRANS.ITEMID
    group by INVOICEDATE, PURCHID