Presto相当于MySQL group_concat

I'm new to Presto and looking to get the same functionality as the group_concat function in MySQL. Are the following two equivalent? If not, any suggestions for how I can recreate the group_concat functionality in Presto?

我是Presto的新手,希望获得与MySQL中的group_concat功能相同的功能。以下两个是等价的吗?如果没有,有关如何在Presto中重新创建group_concat功能的任何建议?

MySQL:

select 
  a,
  group_concat(b separator ',')
from table
group by a

Presto:

select 
  a,
  array_join(array_agg(b), ',')
from table
group by a

(Found this as a suggested Presto workaround here when searching group_concat functionality.)

(在搜索group_concat功能时,可以在此处找到建议的Presto解决方法。)

3 个解决方案

#1

Try using this in place of group_concat in Presto ::

尝试使用它代替Presto中的group_concat ::

select 
  a,
  array_join(array_agg(b), ',')
from table
group by a

#2

There's no function as of this answer, though the feature has been requested.

尽管已经请求了此功能,但此答案没有任何功能。

The closest equivalent is mentioned in your question.

您的问题中提到了最接近的等价物。

WITH tmp AS (
SELECT 'hey' AS str1
UNION ALL
SELECT ' there'
)
SELECT array_join(array_agg(str1), ',', '') AS joined
FROM tmp

#3

Also, if you're looking for unique values only – an equivalent to group_concat(distinct ... separator ', ') – try this:

此外,如果您只查找唯一值 - 相当于group_concat(distinct ... separator',') - 请尝试以下操作:

array_join(array_distinct(array_agg(...)), ', ')

#1