按ID，日期和最后x天的最大值

Question

Supposed I have a table :

 ---------------
 id |  date | value
------------------
  1 |  Jan 1 | 10
  1 |  Jan 2 | 12
  1 |  Jan 3 | 11
  2 |  Jan 4 | 11

I need to get the max and median value of each id, each date, each for the past 90 days. Im using query :

select id, date, value
max(value) over (partition by id, date) as max_date,
median(value) over (partition by id, date) as med_date
from table
where date > date - interval '90 days'

I tried to export the data and check manually but the result is not correct. Any thing I missed? thanks

expected output is to get maximum value of since the last 90 days. for example the date is April 5th, then it will find the maximum value from Jan 5th (the last 90 days) until April 5th. and then the date moves to April 6th, then it will do again for jan 6th until April 6h and so on for each ID

Answer 1

So im assuming u can get several values for same ID and Date and right ? otherwise partitioning for both id and date makes no sense

SELECT id, date, max(value), avg(value) from table where date > date - interval '90 days'
group by id, value

'group by' does the partitioning

Answer 2

Why are you using window functions? This seems to do what you describe:

select id,
       max(value) as max_date,
       percentile_disc(0.5) within group (order by value) as median_value
from table
where date > date - interval '90 days';

If you want this per date , use window functions:

select t.*
from (select t.*,
             max(value) over (order by date range between '89 day' preceding and current row) as running_max_value,
             percentile_disc(0.5) within group (order by value) range between '89 day' preceding and current row) as running_median_value
      from t
     ) t
where date > date - interval '90 days';

The filter is in the outer query so the preceding period can go back further in time.