Я думаю, что следующее должно заставить вас хотеть.
with MYDATA as (
select distinct Account as Act, Company as Cmp, Ledger as Ldgr
from MYTABLE
where Date > Cutoff_Date)
select Account, Company, Ledger, sum(P01), sum(P02)
from MYTABLE join MYDATA
on Account = Act and Company = Cmp and Ledger = Ldgr
group by Account, Company, Ledger