in postgres select, return a column subquery as an array?
Use the aggregate function:
select usr_id, name, array_agg(tag_id) as tag_arrfrom usersjoin tags using(usr_id)group by usr_id, nameor an array constructor from the results of a subquery:
select u.usr_id, name, array( select tag_id from tags t where t.usr_id = u.usr_id ) as tag_arrfrom users uThe second option is simple and fast while the first one is more generic, especially convenient when you need more than one aggregate from a related table.