Question

在MSSQL 2005中计算百分位数排名（例如第90个百分位数或中位数分数）的最佳方法是什么？

我希望能够为单个分数列选择第25个，中位数和第75个百分位数（最好是在单个记录中，这样我可以与平均值，最大值和最小值组合）。例如，结果的表输出可能是：

Group  MinScore  MaxScore  AvgScore  pct25  median  pct75
-----  --------  --------  --------  -----  ------  -----
T1     52        96        74        68     76      84
T2     48        98        74        68     75      85

Answer 1

我认为这是最简单的解决方案：

SELECT TOP N PERCENT FROM TheTable ORDER BY TheScore DESC

其中N =（100 - 期望百分位数）。因此，如果您希望所有行都在第90个百分点，那么您将选择前10％。

我不确定你的意思是“最好是在一张唱片中”。您的意思是计算单个记录的给定分数将落入哪个百分位数？例如你是否希望能够发表诸如“你的分数为83，这使你处于第91百分位”的陈述。？

编辑：好的，我想到了更多关于你的问题并想出了这个解释。您是否在询问如何计算特定百分位数的截止分数？例如这样的事情：要达到第90个百分点，你必须得分大于78。

如果是，则此查询有效。我不喜欢子查询，所以根据它的用途，我可能会尝试找到更优雅的解决方案。但是，它会返回一个单一记录的记录。

-- Find the minimum score for all scores in the 90th percentile
SELECT Min(subq.TheScore) FROM
(SELECT TOP 10 PERCENT TheScore FROM TheTable
ORDER BY TheScore DESC) AS subq

Answer 2

查看NTILE命令 - 它会非常容易地为您提供百分位数！

SELECT  SalesOrderID, 
    OrderQty,
    RowNum = Row_Number() OVER(Order By OrderQty),
    Rnk = RANK() OVER(ORDER BY OrderQty),
    DenseRnk = DENSE_RANK() OVER(ORDER BY OrderQty),
    NTile4  = NTILE(4) OVER(ORDER BY OrderQty)
FROM Sales.SalesOrderDetail 
WHERE SalesOrderID IN (43689, 63181)

Answer 3

这个怎么样：

SELECT
  Group,
  75_percentile =  MAX(case when NTILE(4) OVER(ORDER BY score ASC) = 3 then score  else 0 end),
  90_percentile =  MAX(case when NTILE(10) OVER(ORDER BY score  ASC) = 9 then score  else 0 end)     
FROM TheScore
GROUP BY Group

Answer 4

我一直在研究这个问题，到目前为止我已经提出了这个问题：

CREATE PROCEDURE [dbo].[TestGetPercentile]

@percentile as float,
@resultval as float output

AS

BEGIN

WITH scores(score, prev_rank, curr_rank, next_rank) AS (
    SELECT dblScore,
        (ROW_NUMBER() OVER ( ORDER BY dblScore ) - 1.0) / ((SELECT COUNT(*) FROM TestScores) + 1)  [prev_rank],
        (ROW_NUMBER() OVER ( ORDER BY dblScore ) + 0.0) / ((SELECT COUNT(*) FROM TestScores) + 1)  [curr_rank],
        (ROW_NUMBER() OVER ( ORDER BY dblScore ) + 1.0) / ((SELECT COUNT(*) FROM TestScores) + 1)  [next_rank]
    FROM TestScores
)

SELECT @resultval = (
    SELECT TOP 1 
    CASE WHEN t1.score = t2.score
        THEN t1.score
    ELSE
        t1.score + (t2.score - t1.score) * ((@percentile - t1.curr_rank) / (t2.curr_rank - t1.curr_rank))
    END
    FROM scores t1, scores t2
    WHERE (t1.curr_rank = @percentile OR (t1.curr_rank < @percentile AND t1.next_rank > @percentile))
        AND (t2.curr_rank = @percentile OR (t2.curr_rank > @percentile AND t2.prev_rank < @percentile))
)

END

然后在另一个存储过程中我这样做：

DECLARE @pct25 float;
DECLARE @pct50 float;
DECLARE @pct75 float;

exec SurveyGetPercentile .25, @pct25 output
exec SurveyGetPercentile .50, @pct50 output
exec SurveyGetPercentile .75, @pct75 output

Select
    min(dblScore) as minScore,
    max(dblScore) as maxScore,
    avg(dblScore) as avgScore,
    @pct25 as percentile25,
    @pct50 as percentile50,
    @pct75 as percentile75
From TestScores

它仍然没有完全符合我的要求。这将获得所有测试的统计数据;虽然我希望能够从一个包含多个不同测试的TestScores表中进行选择，并为每个不同的测试获取相同的统计数据（就像我在我的问题中的示例表中所有）。

Answer 5

第50百分位数与中位数相同。计算其他百分位数时，比如80，按升序排序80％数据的数据，按降序排序另外20％的数据，并取两个中间值的平均值。

注意：中位数查询已存在很长时间了，但不记得我从哪里得到它，我只修改了它以计算其他百分位数。

DECLARE @Temp TABLE(Id INT IDENTITY(1,1), DATA DECIMAL(10,5))

INSERT INTO @Temp VALUES(0)
INSERT INTO @Temp VALUES(2)
INSERT INTO @Temp VALUES(8)
INSERT INTO @Temp VALUES(4)
INSERT INTO @Temp VALUES(3)
INSERT INTO @Temp VALUES(6)
INSERT INTO @Temp VALUES(6)
INSERT INTO @Temp VALUES(6) 
INSERT INTO @Temp VALUES(7)
INSERT INTO @Temp VALUES(0)
INSERT INTO @Temp VALUES(1)
INSERT INTO @Temp VALUES(NULL)


--50th percentile or median
SELECT ((
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 50 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA
                ) AS A
        ORDER BY DATA DESC) + 
        (
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 50 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA DESC
                ) AS A
        ORDER BY DATA ASC)) / 2.0


--90th percentile 
SELECT ((
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 90 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA
                ) AS A
        ORDER BY DATA DESC) + 
        (
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 10 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA DESC
                ) AS A
        ORDER BY DATA ASC)) / 2.0


--75th percentile
SELECT ((
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 75 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA
                ) AS A
        ORDER BY DATA DESC) + 
        (
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 25 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA DESC
                ) AS A
        ORDER BY DATA ASC)) / 2.0

Answer 6

我可能会使用sql server 2005

row_number（）结束（按分数排序）/（从分数中选择计数（*））

或类似的东西。

Answer 7

我会做类似的事情：

select @n = count(*) from tbl1
select @median = @n / 2
select @p75 = @n * 3 / 4
select @p90 = @n * 9 / 10

select top 1 score from (select top @median score from tbl1 order by score asc) order by score desc

这是对的吗？

Answer 8

百分位数由

计算

(Rank -1) /(total_rows -1)（按升序对值排序）。

下面的查询将为您提供0到1之间的百分数值。得分最低的人的百分位数为0。

SELECT Name, marks, (rank_1-1)/((select count(*) as total_1 from table)-1)as percentile_rank
from
(
SELECT Name,
       Marks,
       RANK() OVER (ORDER BY Marks) AS rank_1
       from table
) as A

计算MS SQL中的百分位数排名

8 个答案: