Ask in plain English. Get SQL you can check.

SELECT count(*) FROM customers
WHERE status = 'active'
  AND last_order_at > now() - interval '90 days';

SELECT s.name, count(*) AS late
FROM shipments sh
JOIN suppliers s ON sh.supplier_id = s.id
WHERE sh.delivered_at > sh.promised_at
  AND sh.quarter = 'Q3'
GROUP BY 1 ORDER BY 2 DESC;

SELECT region, sum(amount) AS revenue
FROM orders
WHERE date_trunc('month', created_at) = date_trunc('month', now())
GROUP BY 1 ORDER BY 2 DESC;