如何从配置单元中的表中获取组合值

Question

在Hive中有一个具有以下结构的表：

 col1 col2 col3 col4 col5 col6
 -----------------------------
 AA   NM   ER   NER  NER  NER
 AA   NM   NER  ERR  NER  NER
 AA   NM   NER  NER  TER  NER
 AA   NM   NER  NER  NER  ERY

写了一个查询来从表中获取记录：

Select distinct(col1),col2, array(concat(
CASE WHEN col3=='ER'  THEN 'ER' 
     WHEN col4=='ERR' THEN 'ERR'
     WHEN col5=='TER' THEN 'TER'
     WHEN col6=='ERY' THEN 'ERY'
ELSE 'NER' END

但它不起作用。没有得到如何去做。

预期的O / P：

col1 col2 col3
--------------
AA  NM    ['ER','ERR','TER','ERY']

任何建议/提示都会非常有用。

Answer 1

请尝试以下 -

select col1, col2, array(
max(CASE WHEN col3=='ER'  THEN 'ER' else '' end),
max(CASE WHEN col4=='ERR' THEN 'ERR' else '' end),
max(CASE WHEN col5=='TER' THEN 'TER' else '' end), 
max(CASE WHEN col6=='ERY' THEN 'ERY' else '' end))
from table
group by col1, col2

Answer 2

您可以使用concat_ws获取看起来像数组的字符串

Select distinct(col1),col2,concat_ws('','[',
            concat_ws('', "'",col3,"',", "'",col4,"',","'",col5,"',","'",col6,"'"), 
            ']')
from  my_table

Answer 3

这是一个很复杂的问题。我认为简单的解决方案是最简单的解决方案：

select col1, col2, collect_set(col)
from ((select col1, col2, col3 as col from t
      ) union  -- intentional to remove duplicates
      (select col1, col2, col4 as col from t
      ) union  -- intentional to remove duplicates
      (select col1, col2, col5 as col from t
      ) union  -- intentional to remove duplicates
      (select col1, col2, col6 as col from t
      )
     ) t
where col is not null
group by col1, col2;