SELECT 
    ITEM_CODE
    , LAST_DELIVERY_DATE
    , ACTUAL_AMT
    , STOCK_MANAGEMENT_TYPE
    -- *
FROM ITEM LEFT JOIN (
    SELECT 
        ITEM_CODE
        , LAST_DELIVERY_DATE
        , ACTUAL_AMT
        , 1 as STOCK_F
    FROM STOCK
)
USING (ITEM_CODE)
WHERE STOCK_MANAGEMENT_TYPE=1
AND ACTUAL_AMT IS NULL OR STOCK_F=0