如何使用 ANSI SQL 计算百分位数

如何解决如何使用 ANSI SQL 计算百分位数

我想知道是否有人可以帮助我解决以下问题和数据集的以下问题。

仅使用假设关系数据库结构的 ANSI SQL，报告每个站点的后 3 个收入事件和每个站点的第 75 个百分位数的收入。结果应包含三列（网站、收入、第 75 个百分位的收入）。每个网站应包含三行以报告收入最低的 3 个事件（三行将包含相同的网站值和第 75 个百分位的收入）。

"revenue","top","browser","platform","site"
0.00776943843268547,30.9602731291705,"safari","mobile",3
0.014156805607701,9.40058400290278,"chrome","desktop",3
0.0122753797773888,14.1199488319863,3
0.0106614882554566,29.9070545370937,3
0.00947284187142993,19.3632264586303,3
0.00617645820494863,20.6914934615515,4
0.00826814556437385,9.60096864605439,4
0.00632831928919495,9.76504233515594,2
0.00876230897437953,10.7436149034003,2
0.0122542371574979,9.10155570695745,3
0.00734122719327969,11.9796512017936,2
0.00700850269424599,19.4384601758623,2
0.00636258609706847,23.3436268959235,2
0.0106938493186955,8.44233917110576,1
0.0104336231416902,18.2609732065633,1
0.00609590043025647,19.8308911166086,3
0.0132940835699967,12.790110661125,3
0.0143056180039869,14.50619738211,4
0.00410721818995674,17.1302843168817,1
0.0139846720621539,2.28439602214985,4
0.0139832667223559,8.64296576855354,2
0.011386144188017,5.87860889164693,4
0.00967748879893385,4.76435336494166,3    

解决方法

您将使用窗口函数：

select t.*
from (select t.*,row_number() over (partition by site order by revenue desc) as seqnum,percentile_cont(0.75) within group (order by revenue) over (partition by site) as revenue_75
      from t
     ) t
where seqnum <= 3;