问题描述
考虑到我们可能有一行、两行、三行或更多行,我想添加一个计算。我们可以使用关系获取所有数据,但我有点卡住了,因为关系的数量未定义。 例如,作为来源:
SELECT 123 AS id,250 AS amount,225 AS debt,NULL AS relation,1 AS rn
UNION ALL
SELECT 124 AS id,150 AS amount,25 AS debt,123 AS relation,2 AS rn
UNION ALL
SELECT 125 AS id,160 AS amount,50.25 AS debt,124 AS relation,3 AS rn
UNION ALL
SELECT 126 AS id,80 AS amount,125 AS relation,4 AS rn
源表
id | 金额 | 债务 | 关系 | rn |
---|---|---|---|---|
123 | 250 | 225 | NULL | 1 |
124 | 150 | 25 | 123 | 2 |
125 | 160 | 50.25 | 124 | 3 |
126 | 80 | 25 | 125 | 4 |
结束表
id | 金额 | 债务 | 关系 | rn | cal |
---|---|---|---|---|---|
123 | 250 | 225 | NULL | 1 | 250 |
124 | 150 | 25 | 123 | 2 | 22.5 |
125 | 160 | 50.25 | 124 | 3 | 7.5375 |
126 | 80 | 25 | 125 | 4 | 3.75 |
我需要应用如下计算:
- 第 1 行:金额
- 第 2 行:row2.debt*row1.debt/row1.amount
- 第 3 行:row3.debt*row2.debt/row2.amount*row1.debt/row1.amount
- 第 4 行:row4.debt*row3.debt/row3.debt*row2.debt/row2.amount*row1.debt/row1.amount
- 等等。
我正在使用 dbt,但很高兴听到有关 BigQuery 或其他 sql 的消息,因为我真的很好奇如何做到这一点。
解决方法
一点点数学可以帮助这里 - 见下文
select *,ifnull(
round(exp(sum(ln(debt)) over(order by id rows between unbounded preceding and current row))
/ exp(sum(ln(amount)) over(order by id rows between unbounded preceding and 1 preceding)),2),amount
) cal
from `project.dataset.table`
如果应用于您问题中的样本数据 - 输出为
注意:我使用 order by id
假设 id
列定义行的顺序。您可以根据需要进行调整