SQL 从标志中获取 2 个相邻的操作答案

【问题标题】：SQL to get 2 adjacent actions from the flagSQL 从标志中获取 2 个相邻的操作
【发布时间】：2021-05-08 16:43:09
【问题描述】：

希望你一切顺利！

我有一个虚拟数据如下。

我想从每个用户的标志中获取 2 个相邻的操作。

这是描述我想法的图表。

这就是我想要的：

如何实现 SQL（我使用 Google Bigquery）？希望有人可以点亮我。谢谢一百万！

【问题讨论】：

标签： sql group-by google-bigquery sequence partition

【解决方案1】：

你似乎想要lag()。我会将“动作序列”保留为两个单独的列：

select user, prev_action, action, flag
from (select t.*,
             lag(action) over (partition by user order by sequence) as prev_action
      from t
     ) t
where prev_action is not null;

【讨论】：

【解决方案2】：

考虑以下选项

select user, actions.action_sequence, flag  from (
  select *, (
    select as struct count(1) actions_count,
      string_agg(action, ' >> ' order by sequence) action_sequence
    from unnest(arr)
    ) actions
  from (
    select *, array_agg(struct(action, sequence)) 
      over(partition by user order by sequence desc range between current row and 1 following) arr
    from src_table
  ) 
)
where flag != '' 
and actions.actions_count = 2
# order by user, sequence

如果应用于您问题中的样本数据 - 输出是

注意 - 上述解决方案可重复用于您要分析的任意数量的序列 - 不像其他答案中的解决方案被锁定为两个

在此解决方案中 - 您只需将以下几行中的数字（分别为 1 和 2）更改为您需要的任何内容，无需进行其他更改：o)

over(partition by user order by sequence desc range between current row and 1 following) arr

和

and actions.actions_count = 2

例如，如果您将它们分别更改为 2 和 3 - 输出将是

【讨论】：

感谢您的回复。我从答案中学到了很多东西！

【解决方案3】：

试试导航功能LAG：

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LAG(name)
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS preceding_runner
FROM finishers;

+-----------------+-------------+----------+------------------+
| name            | finish_time | division | preceding_runner |
+-----------------+-------------+----------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | NULL             |
| Sophia Liu      | 02:51:45    | F30-34   | NULL             |
| Nikki Leith     | 02:59:01    | F30-34   | Sophia Liu       |
| Jen Edwards     | 03:06:36    | F30-34   | Nikki Leith      |
| Meghan Lederer  | 03:07:41    | F30-34   | Jen Edwards      |
| Lauren Reasoner | 03:10:14    | F30-34   | Meghan Lederer   |
| Lisa Stelzner   | 02:54:11    | F35-39   | NULL             |
| Lauren Matthews | 03:01:17    | F35-39   | Lisa Stelzner    |
| Desiree Berry   | 03:05:42    | F35-39   | Lauren Matthews  |
| Suzy Slane      | 03:06:24    | F35-39   | Desiree Berry    |
+-----------------+-------------+----------+------------------+

【讨论】：