窗口函数：仅对另一列中的不同值求和

Question

注意：这个问题似乎得到了不错的看法，所以我认为最好更新这个问题以清楚起见。大多数更改都是装饰性的，但唯一的主要更改是我在 weights_table 中添加了月份列。权重表是月度表，所以从技术上讲这并不重要，但我想在两个表中都有月份列会使表关系更加明显和合乎逻辑

问题

我有一个使用两个表 [person_table] 和 [weights_table] 的查询。

select 
a.month,
a.movie,
count(a.person_id) as raw,
sum(b.weight) as weighted,
sum(b.weight)/sum(sum(b.weight)) over () as share -- I need to change this calculation 
from (select distinct month, 
                      movie, 
                      person_id 
      from person_table) a 
join weights_table b on a.month=b.month and a.person_id=b.person_id
group by a.month, a.movie;

我想要更改最后一个计算，以便将分母 sum(sum(b.weight)) over () 计算为 (distinct person_ids per month) 的权重总和，而不是 (distinct person_ids per movie per月）。有没有更简单的方法来适应这种情况而无需添加另一个子查询？

person_table 示例

+-------+-------+-----------+
| month | movie | person_id |
+-------+-------+-----------+
|     1 |    a  |         1 |
|     1 |    b  |         1 |
|     1 |    b  |         2 |
|     1 |    a  |         2 |
|     1 |    c  |         3 |
|     1 |    d  |         4 |
|     1 |    a  |         2 |
|     1 |    c  |         3 |
|     1 |    a  |         6 |
+-------+-------+-----------+

weights_table 示例

+-------+-----------+--------+
| month | person_id | weight |
+-------+-----------+--------+
|     1 |         1 |     12 |
|     1 |         2 |     34 |
|     1 |         3 |     65 |
|     1 |         4 |     76 |
|     1 |         7 |     96 |
+-------+-----------+--------+

DDL Fiddle

预期结果

+-------+-------+-----+----------+-------+
| month | movie | raw | weighted | share |
+-------+-------+-----+----------+-------+
|     1 | a     |   2 |       46 |  0.25 | --(12+34)/(12+34+65+76)=0.25
|     1 | b     |   2 |       46 |  0.25 |
|     1 | c     |   1 |       64 |  0.35 |
|     1 | d     |   1 |       76 |  0.41 |
+-------+-------+-----+----------+-------+

指标定义：

原始：每部电影每月所有不同 person_id 的计数）

加权：每部电影每月不同 person_id 的权重总和。

分享：加权与（每月与persons_table匹配的不同person_id的权重总和）的比率

Answer 1

啊，表中只有一个月的数据，并将子选择分解为 CTE 以查看是否可以看到模式。我没有看到任何.. 因此，这似乎是您喜欢 SQL 的方式（对我而言）

with person_table as (
    select column1 as month, column2 as movie, column3 as person_id, column4 as unique_visit_id
    from values (1, 'a', 1, 1),  
        (1, 'b', 1, 2),
        (1, 'b', 2, 3),
        (1, 'a', 2, 4),
        (1, 'c', 3, 5),
        (1, 'd', 4, 6),
        (1, 'a', 2, 7),
        (1, 'c', 3, 8),
        (1, 'a', 6, 9)
), weight_table as (
    select column1 as person_id, column2 as weight
    from values (1, 12), (2, 34), (3, 65), (4, 76), (999,999)
), dis_month_people as (
    select distinct month, person_id 
    from person_table
), month_share as (
    select month, sum(weight) as total_weight
    from dis_month_people dp
    join weight_table w on dp.person_id = w.person_id
    group by 1
), dis_month_movie_people as (
    select distinct month, movie, person_id
    from person_table
)
select t.* --, weighted, total_weight
    ,t.weighted/m.total_weight as share
from (
  select 
    a.month,
    a.movie,
    count(a.person_id) as raw,
    sum(b.weight) as weighted
  from dis_month_movie_people a 
  join weight_table b on a.person_id = b.person_id
  group by 1,2
) AS t
join month_share m on t.month = m.month 
order by 1,2;

Answer 2

可能是这样的：

select a.month,
    a.movie,
    count(a.person_id) as raw,
    sum(b.weight) as weighted,
    100*weighted/c.ttl_weight as share
from (select distinct month, movie, person_id from person_table) a 
inner join weights_table b on a.person_id=b.person_id
cross join (select sum(weight) as ttl_weight from weights_table w
            where exists (select 1 
                          from person_table p 
                          where w.person_id=p.person_id)
           ) c
group by a.month, a.movie, c.ttl_weight
;

Answer 3

万一这个丑陋的解决方法对任何人都有帮助 - 我所做的是缩小子查询/CTE 中的权重，以模拟在外部查询中对唯一权重求和的效果。

select month,
       movie,
       count(distinct person_id) as raw,
       sum(w1) as weighted,
       sum(w1)/1.0/sum(sum(w2)) over() as share
from (select a.*, 
             b.weight/count(*) over (partition by a.month, a.movie, a.person_id) w1, 
             b.weight/count(*) over (partition by a.month, a.person_id) w2
      from person_table a 
      join weights_table b on a.month=b.month and a.person_id=b.person_id) t
group by t.month, t.movie;

我不能说我为这个解决方案感到自豪，因为它只有在我经常查询此类数据时才有用，在这种情况下，将子查询的结果存储在永久月度表中是有意义的。但由于我每月只使用一次或两次，因此我更倾向于使用更高效的查询结构，即使以冗长为代价。