Sql 如何用前一行中的值填充空列？

我想在这里表演一些东西。我想让所有的Colun都充满值。但是当我有空列时，我想让它填充上一个NOTNULL列中的值

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 

在前面的查询中，我已经成功地将值仅放在下一行中

我想做的是让所有列都填充基于上一行的值。 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什么，但我不知道是什么。

这应该与您的

cte

定义相符：

...
select timestamp,
       owner_id,
       owner_assigneddate,
       lastmodifieddate,
       LAST_VALUE(owner_id IGNORE NULLS) 
            OVER(ORDER BY timestamp ASC ROWS BETWEEN 
                 UNBOUNDED PRECEDING AND CURRENT ROW) AS test_column
from cte order by timestamp asc 

---

就问题而言，大查询不支持窗口函数中的

ignorenull

。这里有一个解决方案，它依赖于一个窗口max来定位保存最后一个非空的

所有者id

（这假设时间戳是唯一的）。有了这些信息，您可以将相应的

owner\u id

与join一起引入

select 
    c.timestamp,
    coalesce(c.owner_id, c_lag.owner_id) owner_id,
    c.owner_assigneddate,
    c.lastmodifieddate
from 
    (
        select
            cte.*,
            max(case when owner_id is not null then timestamp end) 
                over(order by timestamp rows unbounded preceding) target_timestamp
        from cte
    ) c
    left join cte c_lag 
        on c.owner_id is null 
        and c_lag.timestamp = c.target_timestamp

：

timestamp | owner_id | owner_assigneddate | lastmodifieddate :------------------ | -------: | :------------------ | :------------------- 2019-11-12 16:01:55 | null | null | null 2019-11-12 19:03:18 | 39530934 | 2019-11-12 19:03:18 | 2019-11-12 19:03:18 2019-11-12 19:03:19 | 39530934 | null | 2019-11-12 19:03:19 2019-11-12 19:03:20 | 39530934 | null | 2019-11-12 19:03:20 2019-11-12 19:03:31 | 40320368 | 2019-11-12 19:03:31 | 2019-11-12 19:03:31 2019-11-12 19:03:33 | 40320368 | null | 2019-11-12 19:03:33 2019-11-12 19:03:56 | 40320368 | null | 2019-11-12 19:03:356

---

在BigQuery中，将

LAST_VALUE（）

与

ignorenulls

选项和

COALESCE（）

一起使用：

select 
    c.timestamp,
    coalesce(c.owner_id, c_lag.owner_id) owner_id,
    c.owner_assigneddate,
    c.lastmodifieddate
from
    cte c
    left join cte c_lag 
        on c.owner_id is null 
        and c_lag.timestamp = c.owner_assigneddate

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