Question

我有一张表，上面列出了旅行次数和station_id，我想返回每个ID最近进行的5次旅行（下表的示例图片）

我在下面进行的查询汇总了车站ID和最近的行程，但是我很难返回最近的5个行程

SELECT start_station_id, MAX(start_time) 
FROM `bpd.shop.trips` 
group by start_station_id, start_time

提示： https://imgur.com/Ebh9FeZ

任何帮助将不胜感激，谢谢！

Answer 1

您可以使用row_number()：

SELECT t.*
FROM (SELECT t.*,
              ROW_NUMBER() OVER (PARTITION BY start_station_id ORDER BY start_time DESC) as seqnum
      FROM `bpd.shop.trips` t
     ) t
WHERE seqnum <= 5;

Answer 2

以下是用于BigQuery标准SQL

选项1

#standardSQL
SELECT record.*
FROM (
  SELECT ARRAY_AGG(t ORDER BY start_time DESC LIMIT 5) arr
  FROM `bpd.shop.trips` t
  GROUP BY start_station_id
), UNNEST(arr) record

选项2

#standardSQL
SELECT * EXCEPT (pos) FROM (
  SELECT *, ROW_NUMBER() OVER(win) AS pos
  FROM `bpd.shop.trips`
  WINDOW win AS (PARTITION BY start_station_id ORDER BY start_time DESC)
) 
WHERE pos <= 5

我建议使用选项1作为更具扩展性的选项

每个ID返回5个最近的旅行

2 个答案: