Question

我有这张桌子：

// controller
$scope.toggleModal = function () {
  $scope.isModalOpen = !$scope.isModalOpen;
}

<div ...
  ng-click="toggleModal()">

<button ng-click="toggleModal()">...

我需要每天显示累积差异。实际上是平均的，但至少应该是累积的。

所以输出看起来像这样：

id
entry_date (timestamp)
exit_date (timestamp)

含义

2015 1 1 33
2015 1 3 56
2015 2 4 77
2015 3 12 123

我检查了类似的主题：

MySQL cumulative sum grouped by date

Cumulative sum over a set of rows in mysql

Optimal query to fetch a cumulative sum in MySQL

Create a Cumulative Sum Column in MySQL

MYSQL request | GROUP BY DAY

但这些解决方案都不适用于我。我正急于用SQL来做这件事。但这些任务听起来很简单，很难相信解决方案很难找到。

Answer 1

你可能能够更有效地工作，但我相信这是让你前进的东西。而且您的解释并不清楚，因此您可能希望提供一些示例数据来阐明您的需求。

select
    event_date,
    (
        select sum(+1) from T as t2 where cast(t2.entry_date as date) <= d.event_date +
        select sum(-1) from T as t3 where cast(t3.exit_date  as date) <= d.event_date
    ) as cumulative_total /* at end of day */
from (
    select cast(entry_date as date) as event_date from T union all
    select cast(exit_date  as date) from T
) as d
group by event_date

将T替换为您的表名。我还使用了一个演员来消除时间，但我不确定它在MySQL中是否真的有效。

平均天数（不包括任何未通过入口或出口表示的日期）也很容易：

select avg(cumulative_total) as average_per_day
from (
    select
        (
            select sum(+1) from T as t2 where cast(t2.entry_date as date) <= d.event_date +
            select sum(-1) from T as t3 where cast(t3.exit_date  as date) <= d.event_date
        ) as cumulative_total /* at end of day */
    from (
        select cast(entry_date as date) as event_date from T union all
        select cast(exit_date  as date) from T
    ) as d
    group by event_date
) as d2

累积总和按天分组

1 个答案: