stripe_invoices_transformed_3.sql

customers as (

  select customer, min(period_start) as active_from, max(period_end) as active_to
  from invoices
  where period_start <= current_date
  group by customer

), customer_dates as (

  select m.date_month, c.customer
  from months m
    inner join customers c
      on m.date_month >= date_trunc('month', c.active_from)
        and m.date_month < date_trunc('month', c.active_to)

)