使用 between 查询时获取最小值最大值所在的日期

Question

有没有办法在某些日期之间查询时获取最小值和最大值发生的日期。

假设我在本月 1 日到 31 日之间进行查询，我想查看该给定列的最小值和最大值发生在哪一天。

Answer 1

您可以使用 window 函数和聚合：

select max(case when seqnum_asc = 1 then col end) as min_val_date,
       max(case when seqnum_desc = 1 then col end) as max_val_date
from (select t.*,
             row_number() over (order by col asc) as seqnum_asc,
             row_number() over (order by col desc) as seqnum_desc
      from t
      where datecol >= ? and datecol < ?
     ) t;

或者你可以只使用聚合：

select (array_agg(datecol order by col desc limit 1))[ordinal(1)] as max_val_date,
       (array_agg(datecol order by col asc limit 1))[ordinal(1)] as min_val_date
from t;
   

Answer 2

考虑下面（如果你关心性能）

select date_of_min, date_of_max
from (
  select date_col as date_of_min from `project.dataset.table` 
  where date_col between min_date and max_date
  order by value_col limit 1
), (
  select date_col as date_of_max from `project.dataset.table` 
  where date_col between min_date and max_date
  order by value_col desc limit 1
)