In every order of operations diagram I’ve seen, SELECT comes essentially near the very end, and always after GROUP BY. However, I find it confusing that in the below SQL statement, we declare aliases in the SELECT statement that can be referenced in the GROUP BY even though GROUP BY happens before SELECT. How is this possible?

SELECT SUM(amount) as 'sum_amt', MONTH(payment_date) as 'm_date'
FROM payment
GROUP BY m_date