计算每月经常性收入变动

SELECT
  date_trunc('month', timestamp_utc) AS month,
  SUM(CASE
    WHEN movement_type IN ('new', 'expansion', 'reactivation')
    THEN mrr_change_usd ELSE 0.0
  END) AS growth_mrr_usd,
  -SUM(CASE
    WHEN movement_type IN ('contraction', 'churn')
    THEN mrr_change_usd ELSE 0.0
  END) AS lost_mrr_usd,
  SUM(mrr_change_usd) AS net_mrr_change_usd,
  COUNT(DISTINCT account_id) AS accounts_changed
FROM billing_events
WHERE timestamp_utc >= now() - INTERVAL '12 months'
GROUP BY date_trunc('month', timestamp_utc)
ORDER BY month;