如何换位

Question

DB：Oracle

我有几个字段，

account cost1 cost2 cost3 cost4 cost5
10       $20   $30   $40   $50   $60
20       $100   $200  $300  $400 $500

要求是

• 如果帐户是10，那么我只需要cost1和cost3

• 如果帐户是20，那么我只需要cost2和cost4

结果应该是这样的，

20----10
40----10
200----20
400----20

有什么建议吗？

Answer 1

使用union all：

select account, cost1 as cost
from t
where account = 10
union all
select account, cost3
from t
where account = 10
union all
select account, cost2
from t
where account = 20
union all
select account, cost4
from t
where account = 20