Forecast cashflow month over month based on historical trends by service

Postgres SQL, as run

select date_trunc('month', billing_period_start at time zone 'UTC') as billing_month,
       case when publisher_name is not null and publisher_name is distinct from invoice_issuer_name then publisher_name else provider_name end as service_provider_name,
       service_category as service_category,
       service_name as service_name,
       sum(billed_cost) as total_billed_cost
from focus.cost_and_usage
where billing_period_start >= $1::timestamptz
  and billing_period_end < $2::timestamptz
group by date_trunc('month', billing_period_start at time zone 'UTC'), case when publisher_name is not null and publisher_name is distinct from invoice_issuer_name then publisher_name else provider_name end, service_category, service_name
order by billing_month asc, total_billed_cost desc nulls last, service_provider_name asc nulls last, service_category asc nulls last, service_name asc nulls last
limit 500

Parameters: $1 = billing_period_start, $2 = billing_period_end

Original FOCUS SQL

SELECT
  MONTH(BillingPeriodStart),
  ServiceProviderName,
  ServiceCategory,
  ServiceName,
  SUM(BilledCost) AS TotalBilledCost
FROM focus_data_table
WHERE BillingPeriodStart >= ? AND BillingPeriodEnd < ?
GROUP BY
  MONTH(BillingPeriodStart),
  ServiceProviderName,
  ServiceCategory,
  ServiceName