년, 월, 성별 별 상품 구매 회원 수 구하기

SELECT YEAR(A.SALES_DATE) AS YEAR,
MONTH(A.SALES_DATE)	AS MONTH,
B.GENDER,
COUNT(DISTINCT(A.USER_ID)) AS USERS
FROM ONLINE_SALE A JOIN USER_INFO B
ON A.USER_ID = B.USER_ID
WHERE B.GENDER IS NOT NULL
GROUP BY YEAR, MONTH, B.GENDER
ORDER BY YEAR, MONTH, B.GENDER;