[英]MySQL - select max value with of sum over year
I have table like:我有这样的表:
v | day | month | year
1 1 1 1950
2 2 1 1950
3 3 1 1950
1 1 2 1950
1 1 2 1951
2 1 2 1952
I have used this query to select MINs我已使用此查询来选择 MIN
SELECT SUM(v) AS sum_val, year, month
FROM `d`
GROUP BY year, month
This will result in这将导致
sum_val | year | month
6 1950 1
1 1950 2
1 1951 2
2 1952 2
How can I select max of sum_val with assigned year grouped by month?如何选择按月分组的指定年份的 sum_val 最大值? I have tried
我试过了
SELECT (MAX(f.sum_val)) AS max_sum, f.year, f.month
FROM (
SELECT SUM(v) AS sum_val, year, month
FROM `d`
GROUP BY year, month
) AS f
GROUP BY month
but this incorrectly assign year to value但这错误地将年份分配给价值
max_sum | year | month
6 1950 1
2 1950 2 <--- should be 1952
SqlFiddle: http://sqlfiddle.com/#!9/ab23b4/6/0 SqlFiddle: http ://sqlfiddle.com/#!9/ab23b4/6/0
You could use some subquery baset on sum_val in join您可以在 join 中使用一些基于 sum_val 的子查询 baset
select t2.sum_val, t2.year, t2.month
from (
SELECT SUM(v) AS sum_val, year, month
FROM `d`
GROUP BY year, month
) t2
INNER JOIN (
select max(sum_val) max_val, year
from (
SELECT SUM(v) AS sum_val, year, month
FROM `d`
GROUP BY year, month
) t
group by year
) t3 on t3.max_val = t2.sum_val and t3.year = t2.year
NB in ths way if you have two rows that match max val the query return two rows请注意,如果您有两行与 max val 匹配,则查询将返回两行
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.