計算總和，平均和DB 90％/ 2

Question

如果我有以下的表稱爲stats：

type duration 
------ --------- 
get  10 
get  15 
get  20 
put  12 
put  14 
put  16 

我知道我能得到sum()和average()用類似的查詢：

select 
    type, 
    sum(duration) as "total duration", 
    avg(duration) as "average duration" 
from 
    stats 
group by 
    type 

而且我還可以使用窗口函數功能獲得90％的持續時間和max()：

select 
    type, 
    avg("dur") as "average duration of the fastest 90%", 
    max("dur") as "max duration of the fastest 90%" 
from 
(
    select 
     type, 
     duration as "dur", 
     row_number() over (partition by type order by duration asc) as "seqnum" 
     count(*) over (partition by type) as "totnum" 
    from 
     stats 
) 
where 
    "seqnum" <= (.9 * "totnum") 
group by 
    type 

但我很努力地瞭解如何將兩者合併，以便我可以有一個查詢返回：type，total duration，average duration,average duration of the fastest 90%,max duration of the fastest 90%？

Answer 1

使用條件彙總：

select type, 
     sum(duration) as "total duration", 
     avg(duration) as "average duration", 
     avg(case when "seqnum" <= (0.9 * "totnum") then "dur" end) as "average duration of the fastest 90%", 
     max(case when "seqnum" <= (0.9 * "totnum") then "dur" end) as "max duration of the fastest 90%" 
from (select type, duration as "dur", 
      row_number() over (partition by type order by duration asc) as "seqnum", 
      count(*) over (partition by type) as "totnum" 
     from stats 
    ) s 
group by type; 

Answer 2

你可以試試這個。

select distinct 
    type, 
    avg("dur") over(partition by type) as "average duration of the fastest 90%", 
    max("dur") over(partition by type) as "max duration of the fastest 90%", 
    "total duration", 
    "average duration" 
from 
(
    select 
     type, 
     duration as "dur", 
     row_number() over (partition by type order by duration asc) as "seqnum", 
     count(*) over (partition by type) as "totnum", 
     sum(duration) over(partition by type) as "total duration", 
     avg(duration) over(partition by type) as "average duration" 
    from 
     stats 
) x 
where 
    "seqnum" <= (.9 * "totnum")