How to pivot rows into columns in AWS Athena?

问题

I'm new to AWS Athena and trying to pivot some rows into columns, similar to the top answer in this StackOverflow post.

However, when I tried:

SELECT column1, column2, column3
FROM data
PIVOT
(
  MIN(column3)
  FOR column2 IN ('VALUE1','VALUE2','VALUE3','VALUE4')
)

I get the error: mismatched input '(' expecting {',', ')'} (service: amazonathena; status code: 400; error code: invalidrequestexception

Does anyone know how to accomplish what I am trying to achieve in AWS Athena?

回答1:

Extending @kadrach 's answer. Assuming a table like this

uid | key | value1 | value2
----+-----+--------+--------
 1  |  A  |  10    | 1000
 1  |  B  |  20    | 2000
 2  |  A  |  11    | 1001
 2  |  B  |  21    | 2001

Single column PIVOT works like this

SELECT
  uid,
  kv1['A'] AS A_v1,
  kv1['B'] AS B_v1
FROM (
  SELECT uid, map_agg(key, value1) kv1
  FROM vtable
  GROUP BY uid
)

Result:

uid | A_v1 | B_v1 
----+------+-------
 1  |  10  |  20   
 2  |  11  |  21

Multi column PIVOT works like this

SELECT
  uid,
  kv1['A'] AS A_v1,
  kv1['B'] AS B_v1,
  kv2['A'] AS A_v2,
  kv2['B'] AS B_v2
FROM (
  SELECT uid,
      map_agg(key, value1) kv1,
      map_agg(key, value2) kv2
  FROM vtable
  GROUP BY uid
)

Result:

uid | A_v1 | B_v1 | A_v2 | B_v2 
----+------+------+------+-----
 1  |  10  |  20  | 1000 | 2000
 2  |  11  |  21  | 1001 | 2001

回答2:

You can do a single-column PIVOT in Athena using map_agg.

SELECT
  uid,
  kv['c1'] AS c1,
  kv['c2'] AS c2,
  kv['c3'] AS c3
FROM (
  SELECT uid, map_agg(key, value) kv
  FROM vtable
  GROUP BY uid
) t

Credit goes to this website. Unfortunately I've not found a clever way to do a multi-column pivot this way (I nest the query, which is not pretty).

回答3:

I had the same issue with using PIVOT function. However I used a turn around way to obtain a similar format data set :

select 
  columnToGroupOn,
  min(if(colToPivot=VALUE1,column3,null)) as VALUE1, 
  min(if(colToPivot=VALUE2,column3,null)) as VALUE2, 
  min(if(colToPivot=VALUE3,column3,null)) as VALUE3 
from
    data
group by columnToGroupOn

来源：https://stackoverflow.com/questions/48013254/how-to-pivot-rows-into-columns-in-aws-athena

标签

sql

amazon-web-services

pivot

amazon-athena