Query: acm_certificate_by_age

with acm_certificates as (
  select
    title,
    created_at,
    to_char(created_at,
      'YYYY-MM') as creation_month
  from
    aws_acm_certificate
),
months as (
  select
    to_char(d,
      'YYYY-MM') as month
  from
    generate_series(date_trunc('month',
        (
          select
            min(created_at)
            from acm_certificates)),
        date_trunc('month',
          current_date),
        interval '1 month') as d
),
certificates_by_month as (
  select
    creation_month,
    count(*)
  from
    acm_certificates
  group by
    creation_month
)
select
  months.month,
  certificates_by_month.count
from
  months
  left join certificates_by_month on months.month = certificates_by_month.creation_month
order by
  months.month;