Ну Вы сами себе и ответили. Только запросик поменять надо немножко:
SELECT
A.ITEMID,
C.ITEMNAME,
B.INVENTLOCATIONID,
SUM(A.POSTEDQTY),
SUM(A.POSTEDVALUE),
SUM(A.PHYSICALVALUE),
SUM(A.DEDUCTED),
SUM(A.REGISTERED),
SUM(A.RECEIVED),
SUM(A.PICKED),
SUM(A.RESERVPHYSICAL),
SUM(A.RESERVORDERED),
SUM(A.ONORDER),
SUM(A.ORDERED),
SUM(A.ARRIVED),
SUM(A.QUOTATIONRECEIPT),
SUM(A.QUOTATIONISSUE),
SUM(A.PHYSICALINVENT),
SUM(A.POSTEDVALUESECCUR_RU),
SUM(A.PHYSICALVALUESECCUR_RU),
SUM(A.AVAILPHYSICAL),
SUM(A.AVAILORDERED)
FROM INVENTSUM A
INNER JOIN INVENTDIM B ON A.INVENTDIMID=B.INVENTDIMID
INNER JOIN INVENTTABLE C ON C.ITEMID=A.ITEMID
GROUP BY A.ITEMID,B.INVENTLOCATIONID
,C.ITEMNAME
ORDER BY
ITEMNAME
Обратно на Axapta сами перевести сможете?