Question

我有一个包含各种群集的记录大小的表以及日期群集的扫描。我需要根据最新扫描日期获取每个群集中每个群集的大小。我在Impala SQL中尝试以下查询，但它不会产生结果。

Scandata    cluster  Size
11/4/2017   ABC 200
11/18/2017  ABC 700
11/25/2017  ABC 1009
12/4/2017   ABC 200
12/18/2017  ABC 700
12/20/2017  ABC 1100
1/4/2018    ABC 200
1/18/2018   ABC 700
1/20/2018   ABC 1009
11/4/2017   CAD 200
11/18/2017  CAD 700
11/25/2017  CAD 1009
12/4/2017   CAD 200
12/18/2017  CAD 700
12/20/2017  CAD 1100

预期结果

Data    cluster  Size
11/25/2017  ABC 1009
12/20/2017  ABC 1100
1/20/2018   ABC 1009
11/25/2017  CAD 1009
12/20/2017  CAD 1100


SELECT t.*
FROM arxview.test_summary t
INNER JOIN
(SELECT MONTH(scandate) AS month, MAX(DAY(scandate)) AS day, cluster
 FROM arxview.test_summary t
 GROUP BY MONTH(scandate), cluster) sub
ON (MONTH(t.scandate) = sub.month AND DAY(t.scandate) = sub.day AND t.cluster = sub.cluster)

Answer 1

另一种方法使用窗口函数：

select ts.*
from (select ts.*,
             max(scandate) over (partition by year(scandate), month(scandate) as max_scandate_monthly
      from arxview.test_summary t
     ) ts
where scandate = max_scandate_monthly;

SQL查询不会产生结果

1 个答案: