Presto equivalent of MySQL group_concat

Question

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?

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.)

Answer 1

Try using this in place of group_concat in Presto ::

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

Answer 2

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

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