sql - 如何使用前一行的值填充空列？

Question

我想在这里表演一些东西。我想让所有的 coluns 都充满了值。但是当我有空列时，我想让它填充上一个非空列的值。

with cte as (
select '2019-11-12 16:01:55' as timestamp, null as owner_id, null as owner_assigneddate, null as lastmodifieddate union all
select '2019-11-12 19:03:18' as timestamp, 39530934 as owner_id, '2019-11-12 19:03:18' as owner_assigneddate, '2019-11-12 19:03:18' as lastmodifieddate union all
select '2019-11-12 19:03:19' as timestamp, null as owner_id, null as owner_assigneddate, '2019-11-12 19:03:19' as lastmodifieddate union all
select '2019-11-12 19:03:20' as timestamp, null as owner_id, null as owner_assigneddate, '2019-11-12 19:03:20' as lastmodifieddate union all
select '2019-11-12 19:03:31' as timestamp, 40320368 as owner_id, '2019-11-12 19:03:31' as owner_assigneddate, '2019-11-12 19:03:31' as lastmodifieddate union all
select '2019-11-12 19:03:33' as timestamp, null as owner_id, null as owner_assigneddate, '2019-11-12 19:03:33' as lastmodifieddate union all
select '2019-11-12 19:03:56' as timestamp, null as owner_id, null as owner_assigneddate, '2019-11-12 19:03:356' as lastmodifieddate)

select timestamp,
       owner_id,
       owner_assigneddate,
       lastmodifieddate,
       COALESCE(owner_id, LEAD(owner_id) OVER(ORDER BY timestamp DESC)) AS test_column
from cte order by timestamp asc 

在上一个查询中，我已经设法将值仅放在下一行中。

我想要做的是让所有列都填充基于前一行的值。
第 4 行的值应为 39530934，第 7 行的值应为 40320368。
我想我在这里遗漏了一些东西，但我不知道是什么。

Answer 1

在 BigQuery 中使用 LAST_VALUE()与 IGNORE NULLS选项和 COALESCE() :

select timestamp,
       COALESCE(owner_id, last_value(owner_id ignore nulls) over (order by timestamp)) as owner_id,
       COALESCE(owner_assigneddate, LAST_VALUE(owner_assigneddate IGNORE NULLS) OVER (ORDER BY TIMESTAMP)) as owner_assigneddate,
       COALESCE(lastmodifieddate, LAST_VALUE(lastmodifieddate IGNORE NULLS) OVER (ORDER BY TIMESTAMP)) as lastmodifieddate
from cte order by timestamp asc