The Final Purchase Report :Find Each Customer’s Most Recent Order Date, ID, and Purchase Amount Intermediate

          with last_order as
  (select customerid,
          orderid,
          totalamount,
          orderdate,
          last_value(orderdate) over (partition by customerid
                                      order by orderdate asc rows between unbounded preceding and unbounded following) as lastorderdate
   from orders)
select customerid,
       orderid,
       totalamount,
       lastorderdate
from last_order
where orderdate = lastorderdate;