SQL 获取特定模式的命令

Question

我有一个 table 样本，列 'observations':

请帮助 SQL 命令获得以下 'cumulative multiplication' 输出：

2
6
30
300

Answer 1

一种方法是递归 CTE：

with tt as (
      select t.*, row_number() over (order by obs) as seqnum
      from t
     ),
     cte as (
      select obs as prod, seqnum
      from tt
      where seqnum = 1
      union all
      select cte.prod * tt.obs, tt.seqnum
      from cte join
           tt
           on tt.seqnum = cte.seqnum + 1
     )
select *
from cte;

另一个使用算术实现一个“乘积”window函数：

select t.*,
       exp(sum(log(obs)) over (order by obs))
from t;

Here 是一个 db<>fiddle.