with tmp as (select * from
item inner join stock on item.item_code=stock.item_code
where
stock.LAST_DELIVERY_DATE is null
or 

(
LAST_DELIVERY_DATE > datetime('2023-06-01','-6 month')
)
or
(
(stock.LAST_DELIVERY_DATE <= datetime('2023-06-01','-6 month') and ACTUAL_AMT>0)
)

)
delete  from item 
where 
not exists (
select 1 from tmp where tmp.item_code=item.item_code)