Hive last_value/first_value实现ignore nulls

最新推荐文章于 2024-08-04 02:19:45 发布

db_guy

最新推荐文章于 2024-08-04 02:19:45 发布

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分类专栏：商业智能-ETL 数据库技术-Oracle SQL 文章标签： hadoop spark hdfs 大数据 hive

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本文介绍如何创建测试表并使用SQL查询，包括使用`last_value`函数按ID和时间顺序获取最新值，展示在默认test_tab表中的数据处理。

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创建一张测试表

drop table if exists default.test_tab purge;
create table default.test_tab
as
select date_add(current_timestamp(),-10) as event_time,'1' as id, 'A' as a,'B' as b,'C' as c
union all select date_add(current_timestamp(),-9) as event_time,'1' as id, 'a' as a, null as b,null as c
union all select date_add(current_timestamp(),-8) as event_time,'1' as id,null as a, 'b' as b,null as c
union all select date_add(current_timestamp(),-7) as event_time,'1' as id,null as a, null as b,'c' as c
union all select date_add(current_timestamp(),-6) as event_time,'2' as id,'AA' as a, null as b,null as c
union all select date_add(current_timestamp(),-5) as event_time,'2' as id,null as a, 'BB' as b,null as c
union all select date_add(current_timestamp(),-4) as event_time,'2' as id,null as a, null as b,'CC' as c
union all select date_add(current_timestamp(),-3) as event_time,'2' as id,'a' as a, 'b' as b,'c' as c;

测试

select t.*, 
    last_value(a) over( partition by id order by event_time) as last_a, 
    last_value(b,TRUE) over( partition by id order by event_time ) as last_b 
from default.test_tab t

结果

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