with t
as(
select a.*,b.updatetime from 采购明细 a
inner join 采购表 b
on a.orderID=b.orderID
)
select * from 物品表 a
where not exists(
select 1 from t where a.PRODUCTID=b.PRODUCTID and datepart(b.updatetime )=5
)

--try

------解决方案--------------------
SQL code
select * from 物品表 a
 where not eixsts(select 1 from 采购表 m,采购明细表n 
   where m.orderID=n.orderID and a.PRODUCTID=n.PRODUCTID and month(m.updatetime)=5)

------解决方案--------------------
select * from 物品表 where 物品编号 not in ( select 物品编号 from 采购明细表 where 采购日期 between 2012-5-1 and 2012-5-31）