Вапрос про SQL-запрос

[richi]

select "ManagerName", sum(jan) as jan , sum(feb) as feb, sum(jun) as jun from
(
select
case when to_char("OrderCreationTime",'mm')='01' then sum("OrderCost") else 0 end as jan,
case when to_char("OrderCreationTime",'mm')='02' then sum("OrderCost") else 0 end as feb,
case when to_char("OrderCreationTime",'mm')='06' then sum("OrderCost") else 0 end as jun,
"ManagerName"
from ordertable
group by "ManagerName",to_char("OrderCreationTime",'mm' )) as q
group by "ManagerName"