如何縮短下面的語句:與日期時間格式比較日期
select * from orders
where to_char(trunc(Cancel_Date,'MONTH'),'dd/mm/yyyy')='01/03/2015'
and state = 'Cancelled'
and to_date(to_char(trunc(Order_Date,'MONTH'),'dd/mm/yyyy'),'dd/mm/yyyy') < to_date('01/03/2015','dd/mm/yyyy')