Double rows retrieved in a simple select

Question

Hi guys, I got an issue that I'm not able to resolve, maybe because I'm exauxted ( I moved more than 600 million of rows today)...anyway:
create table ff (tote varchar, whe date, period int, added date, cost int)
insert into ff values ('A', '2014-01-08', 1, '2014-01-06', 10),
('A', '2014-01-08', 1, '2014-01-07', 10),
('B', '2014-01-09', 1, '2014-01-06', 30),
('B', '2014-01-08', 1, '2014-01-07', 40)
select tote, whe, period, MAX(added), cost
from ff group by tote, whe, period, cost
Having the code above I retrieve three rows.
A 2014-01-08 1 2014-01-07 10
B 2014-01-08 1 2014-01-07 40
B 2014-01-09 1 2014-01-06 30
That's why the cost is different in the tote B. It shouldn't be but with millions of rows you ran into a lot of these errors. The query above inside a procedure works fine ( Is one of the cte on cascade) but in one per cent of case doesn't works because
retrieve the double rows ( as you can see works for the tote A but not for the tote B).
Do you have any suggestion? I need to retrieve one rows per tote having the last added. I would like to avoid self join by the moment that the performance is slow...
Thanks

Answer 1

create table ff (tote varchar(10), whe date, period int, added date, cost int)
insert into ff values ('A', '2014-01-08', 1, '2014-01-06', 10),
('A', '2014-01-08', 1, '2014-01-07', 10),
('B', '2014-01-09', 1, '2014-01-06', 30),
('B', '2014-01-08', 1, '2014-01-07', 40)
;with mycte as (select tote, whe, period, added , cost, row_number() Over(Partition by tote Order by added DESC) rn
from ff )
Select tote, whe, period, added , cost from mycte WHERE rn=1
drop table ff