如何使用下一个非空值填充空列值

Question

我有一个交互表，其中每个交互都分配了一个 id_agent。有些行的 id_agent 具有空值，我想为其分配下一个非空值。我可以使用下一行的前导函数来执行此操作，但是，我有多个连续行的实例，其中 id_agent 为空

当前数据：

id_agent	ts_end_utc	inbound_or_outbound	interaction_channel	id_ticket
-2	2020-09-15 9:40:04	Inbound	supportbot	93789075
299210763	2020-10-10 16:00:23	Outbound	messaging	93789075
Null	2020-10-12 8:46:05	Inbound	messaging	93789075
Null	2020-10-12 10:38:07	Inbound	messaging	93789075
Null	2020-10-15 8:25:23	Inbound	messaging	93789075
234926893	2020-10-15 17:45:58	Outbound	messaging	93789075
299210763	2020-10-28 19:05:49	Outbound	messaging	93789075
Null	2020-11-09 6:50:13	Inbound	messaging	93789075
299210763	2020-11-09 13:03:05	Outbound	messaging	93789075

期望状态：

id_agent	ts_end_utc	inbound_or_outbound	interaction_channel	id_ticket
-2	2020-09-15 9:40:04	Inbound	supportbot	93789075
299210763	2020-10-10 16:00:23	Outbound	messaging	93789075
234926893	2020-10-12 8:46:05	Inbound	messaging	93789075
234926893	2020-10-12 10:38:07	Inbound	messaging	93789075
234926893	2020-10-15 8:25:23	Inbound	messaging	93789075
234926893	2020-10-15 17:45:58	Outbound	messaging	93789075
299210763	2020-10-28 19:05:49	Outbound	messaging	93789075
299210763	2020-11-09 6:50:13	Inbound	messaging	93789075
299210763	2020-11-09 13:03:05	Outbound	messaging	93789075

我知道以后如何使用 case 语句使列看起来符合要求，但我将如何设置逻辑/函数以获取下一个非空值？

Answer 1

你可以使用last_value():

select t.*,
       last_value(id_agent, true) over (order by ts_end_utc) as imputed_id_agent
from t;