求一查询语句，请高手帮忙

Question

表：contno    expcode    amountB00001      A1       100
B00001      A2       200
B00002      A2       400
B00002      A3       500
.............我需要得到如下格式
Contno     A1     A2   A3  ......B00001     100   200
B00001           400   500
........在线等

Answer 1

select xxx.id, sum(xxx.A1),SUM(XXX.A2),SUM(XXX.A3)
from
(select contno   ID, 
       amount   A1 ,
       0        A2,
       0        A3
from tablename
where expcode =A1  
unoin  all 
select contno   ID, 
       0        A1 ,
       amount   A2,
       0        A3
from tablename
where expcode =A2
union all  
select contno   ID, 
       0        A1 ,
       0        A2,
    amount      A3
from tablename
where expcode =A3)xxx
group by xxx.id

Answer 2

select contno,
sum(decode(expcode,'A1',amount,0),
sum(decode(expcode,'A2',amount,0),
sum(decode(expcode,'A3',amount,0),
...
from table 
group by contno