```
SELECT customers.name 
FROM customers 
INNER JOIN orders 
ON customers.id = orders.customer_id 
WHERE EXTRACT(MONTH FROM orders.order_created_at) = '04' 
  AND EXTRACT (YEAR FROM orders.order_created_at) = '2021'
```
Mese: aprile 2021
Scrivi una query in PostgreSQL per elencare i clienti con ordini in un determinato mese.