MySQL 整个时间内按类别的成本

Question

我有一个 table 看起来像这样：

Site | Category | Cost | Month |
A    | Hardware | 10   | 1     |
A    | Software | 30   | 1     |
B    | Software | 15   | 1     |
C    | Labor    | 5    | 2     |
...

我需要输出这个：

Site | Category |  1   |  2  | ...
A    | Hardware | 10   |  0  |
A    | Software | 30   |  0  |
B    | Software | 15   |  0  |
C    | Labor    |  0   |  5  |

将月份属性下的记录用作列 headers 并将成本记录分配到相应月份列下的最佳方法是什么？

Answer 1

SELECT Site, Category, 
   IF(Month=1,Cost,0) as M1,
   IF(Month=2,Cost,0) as M2,
   IF(Month=3,Cost,0) as M3,
   IF(Month=4,Cost,0) as M4,
   IF(Month=5,Cost,0) as M5,
   IF(Month=6,Cost,0) as M6,
   IF(Month=7,Cost,0) as M7,
   IF(Month=8,Cost,0) as M8,
   IF(Month=9,Cost,0) as M9,
   IF(Month=10,Cost,0) as M10,
   IF(Month=11,Cost,0) as M11,
   IF(Month=12,Cost,0) as M12
FROM tablename

会逐行给出。如果你想要每个 Category

一行，你可以添加一个 GROUP BY

SELECT Site, Category, 
   SUM(IF(Month=1,Cost,0)) as M1,
   SUM(IF(Month=2,Cost,0)) as M2,
   SUM(IF(Month=3,Cost,0)) as M3,
   SUM(IF(Month=4,Cost,0)) as M4,
   SUM(IF(Month=5,Cost,0)) as M5,
   SUM(IF(Month=6,Cost,0)) as M6,
   SUM(IF(Month=7,Cost,0)) as M7,
   SUM(IF(Month=8,Cost,0)) as M8,
   SUM(IF(Month=9,Cost,0)) as M9,
   SUM(IF(Month=10,Cost,0)) as M10,
   SUM(IF(Month=11,Cost,0)) as M11,
   SUM(IF(Month=12,Cost,0)) as M12
FROM tablename
GROUP BY Site, Category

将保留网站，但总结类别。

此外，如果您不喜欢该字段的 Mx 名称，您可以尝试使用 '1' .. '2' etc.I 认为它应该有效

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