Re: How-To: Aggregate data from multiple rows into a delimited list.

["Pavel Stehule" <pavel.stehule@xxxxxxxxx>]

> The query would become
>  SELECT a.id, a.name, array_acc(b.name) as b_names
>  FROM a LEFT JOIN b USING(id)
>  GROUP BY a.id, a.name;

All variants are possible. Variant with array_to_string is faster and
doesn't need own aggregate function. And you can easy remove
duplicities.

SELECT a.id, a.name,
     ARRAY_TO_STRING(ARRAY(
       SELECT DISTINCT b.name
       FROM b
       WHERE b.id = a.id
       ORDER BY b.name ASC
     ), ',') AS b_names
   FROM a
   ORDER BY a.id ASC;

regards
Pavel