antoine-lizee · October 21, 2020 01:45
diff --git a/medium_cte_and_optim_1.sql b/medium_cte_and_optim_1.sql
 -- Show the distribution of customers per number of orders in 2020:
 WITH n_orders_by_customer AS (
    SELECT customer_id, count(*) AS n_orders
    FROM orders
    WHERE paid_date > '2020-01-01'
    GROUP BY 1
 )
 SELECT n_orders, count(*) AS n_customers
 FROM n_orders_by_customer
 GROUP BY 1
	-- Show the distribution of customers per number of orders in 2020:
	WITH n_orders_by_customer AS (
	SELECT customer_id, count(*) AS n_orders
	FROM orders
	WHERE paid_date > '2020-01-01'
	GROUP BY 1
	)
	SELECT n_orders, count(*) AS n_customers
	FROM n_orders_by_customer
	GROUP BY 1