oracle sum() 急 急！

Question

select cd.cust_code,sp.currency, 
 case when cd.eta>=to_date('2011-01-01','yyyy-mm-dd') and cd.eta<to_date('2011-02-01','yyyy-mm-dd') then  sum(cd.cfc_qty*sp.price)  as Jan_Amount
      when cd.eta>=to_date('2011-02-01','yyyy-mm-dd') and cd.eta<to_date('2011-03-01','yyyy-mm-dd') then  sum(cd.cfc_qty*sp.price)  as Feb_Amount
      when cd.eta>=to_date('2011-03-01','yyyy-mm-dd') and cd.eta<to_date('2011-04-01','yyyy-mm-dd') then  sum(cd.cfc_qty*sp.price)  as Mar_Amount
      else 0
      end as cd.cfc_qty*sp.price
from cfc_detail cd,selling_price sp
 where sp.cust_code =cd.cust_code
 group by cd.cust_code,
          sp.currency 
order by cd.cust_code
 我要按客户查询 一月 ，二月和三月的销售额  以上sQl有错，求正解！
输出格式为
cust_code   currency   Jan_Amount   Feb_Amount   Mar_Amount

Answer 1

select a.cust_code,
       a.currency,
       sum(a.Jan_Amount) as Jan_Amount,
       sum(a.Feb_Amount) as Feb_Amount,
       sum(a.Mar_Amount) as Mar_Amount
  from (select a.cust_code,
               b.currency,
               a.eta,
               decode(trunc(a.eta, 'mm'),
                      to_date('2011-01-01', 'yyyy-mm-dd'),
                      sum(a.cfc_qty * b.price)) as Jan_Amount,
               decode(trunc(a.eta, 'mm'),
                      to_date('2011-02-01', 'yyyy-mm-dd'),
                      sum(a.cfc_qty * b.price)) as Feb_Amount,
               decode(trunc(a.eta, 'mm'),
                      to_date('2011-03-01', 'yyyy-mm-dd'),
                      sum(a.cfc_qty * b.price)) as Mar_Amount
        
          from cfc_detail a, selling_price b
         where a.cust_code = b.cust_code
         group by a.cust_code, b.currency, a.eta
         order by a.cust_code) a
 group by a.cust_code, a.currency;