История изменений
Исправление maxcom, (текущая версия) :
select distinct on (month) date_trunc('month', enter_date) as month, enter_date, amount from budget order by month, enter_date desc
Исходная версия maxcom, :
select distinct on (month) date_trunc('month', enter_date) as month, amount from budget order by month, enter_date desc