求一查询语句，请高手帮忙
表：

contno         expcode         amount

B00001             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


------解决方案--------------------
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
------解决方案--------------------
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