平均數及中位數在SQL Server一個查詢2012

Question

我在我的表中的以下數據：

SELECT category, value FROM test 

 
| category | value | 
+----------+-------+ 
| 1  | 1 | 
| 1  | 3 | 
| 1  | 4 | 
| 1  | 8 | 

現在我使用兩個單獨的查詢。

1. 爲了得到平均：

   SELECT category, avg(value) as Average 
       FROM test 
   GROUP BY category 
   

    
   | category | value | 
   +----------+-------+ 
   | 1  | 4 | 
   

2. 要獲得中位數：

   SELECT DISTINCT category, 
          PERCENTILE_CONT(0.5) 
           WITHIN GROUP (ORDER BY value) 
           OVER (partition BY category) AS Median 
         FROM test 
   

    
   | category | value | 
   +----------+-------+ 
   | 1  | 3.5 | 
   

有什麼辦法可以將它們合併到一個查詢中嗎？

注意：我知道我也可以通過兩個子查詢獲得中值，但我更喜歡使用PERCENTILE_CONT函數來獲取它。

Answer 1

AVG也是一個窗口函數：

select 
distinct 
category, 
avg(value) over (partition by category) as average, 
PERCENTILE_CONT(0.5) 
        WITHIN GROUP (ORDER BY value) 
        OVER (partition BY category) AS Median 
        from test 

Answer 2

我會在一個稍微不同的方式處理這個：

select category, avg(value) as avg, 
     avg(case when 2 * seqnum in (cnt, cnt + 1, cnt + 2) then value end) as median 
from (select t.*, row_number() over (partition by category order by value) as seqnum, 
      count(*) over (partition by category) as cnt 
     from test t 
    ) t 
group by category;