delete from ITEM
where
    STOCK_MANAGEMENT_TYPE = 1
and (
    not exists(
        select  ITEM_CODE
        from    STOCK
        where   ITEM.ITEM_CODE = STOCK.ITEM_CODE
    )
or  (
        select  IFNULL(LAST_DELIVERY_DATE, '2999-12-31')
        from    STOCK
        where   ACTUAL_AMT = 0
    ) <= DATE ('2023-06-01', '-6 months')
)