平均数及中位数在SQL Server一个查询2012

Question

我在我的表中的以下数据：

SELECT category, value FROM test 

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

现在我使用两个单独的查询。

1. 为了得到平均：

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

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

2. 要获得中位数：

   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 | 
   

有什么办法可以将它们合并到一个查询中吗？

注意：我知道我也可以通过两个子查询获得中值，但我更喜欢使用PERCENTILE_CONT函数来获取它。

Answer 1

AVG也是一个窗口函数：

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

我会在一个稍微不同的方式处理这个：

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;