MySQL查询按年龄、3个月、6个月、9个月和12个月分组

Question

+------+------------+ 
| cost | date       |
+------+------------+ 
|   44 | 2015-04-30 | 
|   39 | 2015-04-31 | 
|   18 | 2015-04-01 | 
|   71 | 2015-01-02 | 
|   69 | 2014-12-03 | 
|   62 | 2014-12-04 | 
|   89 | 2014-08-05 | 
|   72 | 2014-08-06 | 
|   46 | 2014-05-07 | 
|   23 | 2014-05-08 |
+------+------------+

根据上表，我想编写一个查询来区分从现在起 3 个月、6 个月、9 个月和 1 年前的总成本。

我该怎么做？

Answer 1

您可以在group by中放置case语句:

select (case when date >= date_sub(now(), interval 3 month) then '3month'
             when date >= date_sub(now(), interval 6 month) then '6month'
             when date >= date_sub(now(), interval 9 month) then '9month'
             when date >= date_sub(now(), interval 12 month) then '12month'
        end) as grp, sum(cost) as sumcost
from table t
where date >= date_sub(now(), interval 12 month)
group by grp;