根据窗口函数最大值获取其他列，Bigquery答案

【问题标题】：Get Other Columns based on window function maximum value, Bigquery根据窗口函数最大值获取其他列，Bigquery
【发布时间】：2021-11-25 18:35:14
【问题描述】：

如何获取over子句中窗口函数给出输出的同一行的整行或其他列值。

例如

with o as (
    select date from unnest(GENERATE_TIMESTAMP_ARRAY('2021-01-01 00:00:00',current_timestamp(),interval 1 hour)) as date
enter code here
), p as (
    select *,RAND()*100 as Number from o
), q as (
    select *,max(number) over(order by date) as best from p
    order by date
)
select * from q

使用上面的查询，我得到的输出是最好的值，它在按时间戳排序时定义了我上面的最大数量。

上列的输出：

我使用 over 函数计算了最佳值，但我还想要日期列在哪一天最好。

【问题讨论】：

我了解，您需要另一列 best_date 例如 (2021-01-01 21:00:00 UTC)？

标签： sql google-bigquery max window-functions

【解决方案1】：

也许是这个？

with o as (
    select date from unnest(GENERATE_TIMESTAMP_ARRAY('2021-01-01 00:00:00',current_timestamp(),interval 1 hour)) as date
), p as (
    select *,RAND()*100 as Number from o
), q as (
    select *,max(number) over(order by date) as best from p
)
select * except(date_new_best), max(date_new_best) over (order by date) as date_best 
from (
    select *, if(number=best, date, NULL) as date_new_best
    from q
)
order by date

【讨论】：

【解决方案2】：

考虑以下方法

with o as (
    select date from unnest(GENERATE_TIMESTAMP_ARRAY('2021-01-01 00:00:00',current_timestamp(),interval 1 hour)) as date
), p as (
    select *,RAND()*100 as Number from o
), q as (
    select *,max(number) over(order by date) as best from p
)
select * except(best_date),
  last_value(best_date ignore nulls) over(order by date) as best_date
from (
  select *, if(best = lag(best) over(order by date), null, date) best_date
  from q
)

输出如下

【讨论】：