--商品コード(ITEM_CODE)が存在しない
DELETE 
FROM
    ITEM 
WHERE
    STOCK_MANAGEMENT_TYPE = 1  AND  
    ITEM_CODE NOT IN (SELECT ITEM_CODE  FROM STOCK);
    
--存在しても、商品毎の最終出荷日(LAST_DELIVERY_DATE)の最大値が6カ月以上前で実在庫数(ACTUAL_AMT)がゼロのデータ
DELETE 
FROM
    ITEM 
WHERE
    STOCK_MANAGEMENT_TYPE = 1  AND  
    ITEM_CODE IN (SELECT ITEM_CODE  FROM STOCK);