1. 월 별 매출액 분석 1.1 월 별 매출액, 주문건수, 구매자수 추출 SELECT to_char(o.order_date, 'YYYY-MM') AS order_month , sum(od.unit_price * od.quantity * (1-od.discount)) AS sales , count(DISTINCT o.order_id) AS 주문건수 , count(DISTINCT c.customer_id) AS 구매자수 FROM orders o INNER JOIN order_details od ON o.order_id = od.order_id INNER JOIN customers c ON o.customer_id = c.customer_id GROUP BY 1 ORDER BY 1; 1.2 월 별 인당 평균 ..
