MySQL中按年份和月份分组

Question

我有一个包含25个日期列的表。现在我正在用PHP构建一个应用程序，并且必须显示基于月和年的摘要。我已经提到了下面的源表格布局和预期的汇总表。

这里ID代表每一行。源表ID将在汇总表中使用。汇总表将每年创建一次。我需要一些帮助来准备这个汇总表。在这里我想提一提，我将在源桌上有大约30K行。

源表：

ID | DATE 1  | DATE 2  | DATE 3 
-------------------------------------------------- 
1 | 2017-01-14 | 2017-01-19 | 2017-01-25 
2 |    | 2017-03-19 | 2017-03-25 
3 | 2017-03-15 |    | 2017-05-25 
4 | 2017-04-24 | 2017-05-19 | 
5 | 2017-04-10 | 2017-06-19 | 2017-07-25 
6 | 2017-05-11 | 2017-06-19 | 2017-08-25 

汇总表

ID | YEAR | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC 
------------------------------------------------------------------------------------ 
1 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 
2 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 
3 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 
4 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 
5 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 
6 | 2017 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 

Answer 1

您需要unpivot的数据，并重新聚集它。查询结构为：

select id, year(date) as yyyy, 
     sum(month(date) = 1) as Jan, 
     sum(month(date) = 2) as Feb, 
     . . . 
     sum(month(date) = 12) as Dec 
from ((select id, date1 as date from source) union all 
     (select id, date2 as date from source) union all 
     . . . 
     (select id, date25 as date from source) 
    ) d 
where date is not null 
group by id, year(date) 
order by id, year(date); 

. . .表示填写空格。