Get first entry from an associated table Ruby on Rails -

i have 1 many relationship: user has many payments. trying find query gets first payment of each user(using created_at payments table).

i have found similar question sql response, have no idea how write active record.

how query sql latest record date each user

quoting answer:

select t.username, t.date, t.value mytable t inner join (     select username, max(date) maxdate     mytable     group username ) tm on t.username = tm.username , t.date = tm.maxdate 

for me, min instead of max.

thank :)

try 1 postgres

payment.select("distinct on(user_id) *").order("user_id, created_at asc") 

and sql

payment.group(:user_id).having('created_at = max(created_at)')