query splitting out joule / premium sales

sales.sql

SELECT 
	SUM(joule_sale) as joule_sales,
	SUM(premium_sale) as premium_sales,
	date
FROM (
	SELECT 
		CASE WHEN amount > 15000 THEN 1 ELSE NULL END as joule_sale,
		CASE WHEN amount < 15000 THEN 1 ELSE NULL END as premium_sale,
		date_trunc('day', occurred_at - interval '8 hours') as date
	FROM 
		stripe_charges 
	WHERE 
		occurred_at - interval '8 hours' > '2015-11-17' -- UTC of our launch date
) z
GROUP BY
	date
ORDER BY 
	date DESC