Returning a fixed value list
select * from
(Values(1, 'one'), (2, 'two'), (3, 'three'))
as t(num, letter)
Filtering counts
SELECT
EXTRACT(MONTH FROM payment.payment_date) AS month,
SUM(amount)::decimal(18,2) AS total_amount,
COUNT(payment_id) AS total_count,
COUNT(payment_id) FILTER (WHERE staff_id = 1) AS mike_count,
SUM(amount) FILTER (where staff_id = 1) AS mike_amount,
FROM payment
GROUP BY month
ORDER BY month
