DELETE
FROM
    ITEM
WHERE
    ITEM_CODE IN(
                    SELECT 
                        ITEM_CODE
                    FROM 
                        STOCK
                    WHERE 
                        ITEM_CODE NOT IN (SELECT ITEM_CODE FROM ITEM) OR 
                        LAST_DELIVERY_DATE < date('now', '-6 months') AND 
                        ACTUAL_AMT = 0)