在Oracle中查询时间段[重复]

Question

我有如下问题，当我查询时，如何返回不同时间段不同列的总和，比如我有这张表：

  ---------------------------
  | PRODUCT | VALUE | MONTH |
  ---------------------------
  | P1      | 10    |  2    |
  | P1      |  5    |  3    |
  | P1      |  22   |  4    |
  | P1      |  4    |  2    |
  | P2      |  4    |  2    |
  | P2      |  7    |  4    |
  | P2      |  10   |  4    |

我希望我有这个结果

  --------------------------------------
  | PRODUCT | MONTH2 | MONTH3 | MONTH4 |
  --------------------------------------
  | P1      | 14       |  5    | 22    |
  | P2      | 4        |  0    | 17    |

Answer 1

您可以使用条件聚合：

select product,
       sum(case when month = 2 then value end) as month2,
       sum(case when month = 3 then value end) as month3,
       sum(case when month = 4 then value end) as month4
from t
group by product;