SQLSERVER 中位数

       用SQLSERVER取中位数，比较着急，先这么写了，在论坛里发了个帖子https://bbs.csdn.net/topics/397444283，有更好的写法，欢迎讨论，代码如下：

--测试数据
if not object_id(N'Tempdb..#T') is null
	drop table #T
Go
Create table #T([id] INT,tcount DECIMAL(18,2))
Insert #T
select 1,1 union all
select 1,2 union all
select 1,3 union ALL
select 1,4 union ALL
select 1,5 union all
select 2,6 union all
select 2,7 union all
select 3,8
Go
--测试数据结束
;WITH cte AS (
SELECT id,tcount,
       COUNT(1) OVER (PARTITION BY id) cou,
       ROW_NUMBER() OVER (PARTITION BY id ORDER BY tcount) rn
FROM #T
)
SELECT id,AVG(cte.tcount) AS 中位数 FROM cte WHERE rn = cte.cou/2+1 AND cte.cou%2=1 GROUP BY cte.id
UNION ALL
SELECT a.id,
       sum(a.tcount + ISNULL(b.tcount, 0))/2
FROM cte a
    LEFT JOIN cte b
        ON a.id = b.id
WHERE a.rn = a.cou/2
      AND a.cou % 2 = 0
      AND b.rn = a.rn + 1
GROUP BY a.id
ORDER BY id

       结果：