For each month, compute the patient visit rate, revenue requirement, and average billing per patient.

First, extract the month from visit_date. Then join visits with billing to get amounts. Count distinct visits for visit rate, sum amounts for revenue, and average amounts for billing per patient. Example:

SELECT DATE_TRUNC('month', v.visit_date) AS month,

   COUNT(DISTINCT v.visit_id) AS visit_rate,
   SUM(b.amount) AS revenue,
   AVG(b.amount) AS avg_billing_per_patient

FROM visits v

JOIN billing b ON v.visit_id = b.visit_id

GROUP BY month

ORDER BY month;

This query returns, for each month, how many visits occurred, the total revenue generated, and the average billing amount per patient.