Question

我正在尝试基于DateTime行计算当前行和前4行之间的两列“ Weight”和“ Volume”的滚动总和。这些是日志负载，有些日子我们会收到多个负载。因此，从本质上讲，每次引入新的负载时，它将基于自身和前4行计算出新的滚动总和。我正在使用MySQL 5.7。请记住，每一行都不是新日期。数据应该看起来像这样...

         DateTime       | Weight | Volume | Roll_Weight | Roll_Volume
    2019-01-01 08:00:00 | 54000  | 72.2   |   54000     |   72.2
    2019-01-01 09:30:00 | 29000  | 38.0   |   83000     |  110.2
    2019-01-05 13:00:00 | 38900  | 54.8   |  118900     |  165.0 
    2019-01-06 07:00:00 | 44000  | 56.2   |  162900     |  221.2
    2019-01-06 12:30:00 | 49000  | 18.0   |  211900     |  239.2
    2019-01-07 09:00:00 | 27900  | 84.5   |  185800     |  251.5
    2019-01-10 08:00:00 | 94000  | 72.6   |  250800     |  286.1
    2019-01-10 13:30:00 | 65000  | 39.7   |  286800     |  271.0
    2019-01-10 15:00:00 | 38900  | 50.5   |  274800     |  265.3

Select DateTime, Sum(Weight), Sum(Volume) over (Partition by DateTime ORDER BY DateTime asc 4 preceding)
From t1

我知道，因为我使用的是MySQL 5.7，所以我没有使用OVER的功能，但这似乎正是我所需要的。解决此问题的最佳方法是什么？我发现的所有资源的每一行都有不同的日期，因此它们只对日期使用自我联接查询，但是我不能这样做，因为我要逐行滚动。

Answer 1

我们可以在 DateTime 之前COALESCE将 Weight 和 Volume 的前4个值+向上SELECT `DateTime`, Weight, Volume, Weight + COALESCE((SELECT Weight FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `Date` DESC LIMIT 0, 1), 0) + COALESCE((SELECT Weight FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `Date` DESC LIMIT 1, 1), 0)+ COALESCE((SELECT Weight FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `DateTime` DESC LIMIT 2, 1), 0)+ COALESCE((SELECT Weight FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `DateTime` DESC LIMIT 3, 1), 0) AS RollWeight, Volume + COALESCE((SELECT Volume FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `Date` DESC LIMIT 0, 1), 0) + COALESCE((SELECT Volume FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `Date` DESC LIMIT 1, 1), 0)+ COALESCE((SELECT Volume FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `DateTime` DESC LIMIT 2, 1), 0)+ COALESCE((SELECT Volume FROM t1 AS t2 WHERE t2.`DateTime` < t3.`DateTime` ORDER BY `DateTime` DESC LIMIT 3, 1), 0) AS RollVolume FROM t1 AS t3;并带有各自的当前值

__r<OPERATOR>__

基于行计算滚动总和

1 个答案: