apache-spark - 如何通过聚合在 Hive 中透视数据

Question

我有一个如下所示的表数据，我想通过聚合来旋转数据。

ColumnA    ColumnB            ColumnC
1          complete            Yes
1          complete            Yes
2          In progress         No
2          In progress         No 
3          Not yet started     initiate 
3          Not yet started     initiate 

想要像下面这样旋转

ColumnA          Complete    In progress     Not yet started
1                 2               0                0
2                 0               2                0
3                 0               0                2

我们是否可以在 hive 或 Impala 中实现这一目标？

Answer 1

使用 case 和 sum 聚合:

select ColumnA,    
       sum(case when ColumnB='complete'        then 1 else 0 end) as Complete,
       sum(case when ColumnB='In progress'     then 1 else 0 end) as In_progress,
       sum(case when ColumnB='Not yet started' then 1 else 0 end) as Not_yet_started
  from table
 group by ColumnA
 order by ColumnA --remove if order is not necessary
;