sql - 对一列求和，直到另一列中的特定值

Question

我有一个表格，按执行顺序列出活动及其持续时间，即表格按时间排序。它主要有四列：

person_ID、duration、activity_ID、time

如何将持续时间相加，直到达到某个 activity_ID？activity_ID 描述的活动可以按任何顺序出现。

例如，该表可以列出您白天的活动，例如起床、淋浴、刮胡子、吃饭、穿衣、穿鞋。顺序和活动因人和天而异。

我想总结所有活动的持续时间，直到某个活动（例如“穿衣服”）然后停止。我如何在 sql 中执行此操作？

Answer 1

不确定这是否是您要查找的内容，而是一种通用技术：根据您是否要包含它来打开或关闭一行的标志，然后将所有带有该标志的记录相加。

create table activity( person_ID number, duration number, activity_ID number)

insert into activity values(1, 1, 1);
insert into activity values(1, 2, 2);
insert into activity values(1, 3, 3);
insert into activity values(1, 4, 4);
insert into activity values(1, 5, 5);

insert into activity values(2, 10, 1);
insert into activity values(2, 20, 2);
insert into activity values(2, 30, 3);
insert into activity values(2, 40, 4);
insert into activity values(2, 50, 5);

SELECT person_id, SUM( CASE WHEN activity_id <= 3 THEN duration ELSE 0 END ) AS sum_till_3
  FROM activity
  GROUP BY person_id
  ORDER BY person_id

PERSON_ID SUM_TILL_3
--------- ----------
        1          6 
        2         60 

Answer 2

以下是使用常规窗口函数的方法：

select t.user_id, sum(time <= activity_time then duration else 0 end)
from (select t.*,
             min(activitytime) over (partition by user_id) as activitytime
      from (select t.*,
                   (case when activity_id = xxx then 1 else 0 end) as isactivity,
                   (case when activity_id = xxx then time end) as activitytime,
            from t
           ) t
      ) t
group by user_id

这只是找到每个用户发生活动的最短时间，然后将他们的持续时间相加。