检索最近发布日期的每个城市的最近5天预测

Question

我需要检索每个城市的最近5天预测信息。

我的表看起来像下面

真正的问题是发行日期。

该城市可能包含具有不同发布日期的同一日期的多个预测信息。

我需要通过预测日期检索最近的5条记录与最新发布日期组中的每个城市

我试图像下面，但没有给出预期的结果

SELECT * FROM(
SELECT 
    ROW_NUMBER() OVER (PARTITION BY CITY_ID ORDER BY FORECAST_DATE DESC, ISSUE_DATE DESC) AS rn, 
    CITY_ID, FORECAST_DATE, ISSUE_DATE 
FROM 
    FORECAST  
GROUP BY FORECAST_DATE 
) WHERE rn <= 5 

任何建议或意见将有帮助

Answer 1

这将让每天最新的已发行预测在最近的5天，每个城市：

SELECT * 
FROM (
    SELECT f.*, 
     DENSE_RANK() OVER (PARTITION BY city_id ORDER BY forecast_date DESC) 
      AS forecast_rank, 
     ROW_NUMBER() OVER (PARTITION BY city_id, forecast_date ORDER BY issue_date DESC) 
      AS issue_rn 
    FROM Forecast f 
) 
WHERE forecast_rank <= 5 
AND issue_rn = 1; 

Answer 2

Partition by作品像group by但仅限于该功能。

尝试

with CTE as 
(
select t1.*, 
     row_number() over (partition by city_id, forecast_date order by issue_date desc) as r_ord 
from Forecast 
) 
select CTE.* 
from CTE 
where r_ord <= 5 

Answer 3

试试这个

SELECT * FROM(
    SELECT 
     ROW_NUMBER() OVER (PARTITION BY CITY_ID, FORECAST_DATE order by ISSUE_DATE DESC) AS rn, 
     CITY_ID, FORECAST_DATE, ISSUE_DATE 
    FROM 
     FORECAST  
    ) WHERE rn <= 5