Måneder mellem to datoer fungerer

Dette er nemt at genimplementere i PostgreSQL ved blot at bruge SQL-funktioner til at rydde op i det, du allerede har:

create function months_of(interval)
 returns int strict immutable language sql as $$
  select extract(years from $1)::int * 12 + extract(month from $1)::int
$$;

create function months_between(date, date)
 returns int strict immutable language sql as $$
   select abs(months_of(age($1, $2)))
$$;

Og nu select months_between('1978-06-20', '2011-12-09') producerer 401.