Postgres array concatenation function

Question

Does Postgres have a function to transform an array into a single value? For example, I'd like to do something like:

reduce(ARRAY['one','two']) -> onetwo , or even better: reduce(ARRAY['one','two], ', ') -> one, two

If not, how would I go about implementing that in my query. I know of unnest , but that just gives me one row per array element

Answer 1

As in the comments:

select array_to_string(array['one','two'],',');
 array_to_string 
-----------------
 one,two