如何在 Oracle 的选择列中显示月份？ [复制]

Question

我的数据库中有一组数据 - 请参见以下示例：

Food      CONSUMPTION  DATE_INSERTED
--------  -----------  -------------
Burger              2  07/10/2021
Fries               1  08/10/2021
Burger              2  08/10/2021
Chicken             1  07/12/2021
Burger              1  08/15/2021
Fries               2  08/11/2021   

有了这个，我想创建一个这样的查询来显示这个输出：

Food      July  August  September  October
--------  ----  ------  ---------  -------
Burger       2       3          0        0
Fries        0       3          0        0
Chicken      1       0          0        0

我实际上是在 SQL Server 中执行此操作，但我很难在 Oracle 中显示输出。

Answer 1

方法如下。

SQL> select food,
  2    sum(case when to_char(date_inserted, 'mm') = '07' then consumption else 0 end) as July,
  3    sum(case when to_char(date_inserted, 'mm') = '08' then consumption else 0 end) as August,
  4    sum(case when to_char(date_inserted, 'mm') = '09' then consumption else 0 end) as September,
  5    sum(case when to_char(date_inserted, 'mm') = '10' then consumption else 0 end) as October
  6  from food
  7  group by food
  8  order by food;

FOOD             JULY     AUGUST  SEPTEMBER    OCTOBER
---------- ---------- ---------- ---------- ----------
Burger              2          3          0          0
Chicken             1          0          0          0
Fries               0          3          0          0

SQL>

如果需要/必须添加其他月份，也可以添加。