▶ 학습내용
SELECT YEAR(O.SALES_DATE)AS YEAR,MONTH(O.SALES_DATE)AS MONTH,U.GENDER,COUNT(DISTINCT O.USER_ID) AS USERS
FROM USER_INFO AS U INNER JOIN ONLINE_SALE AS O ON U.USER_ID=O.USER_ID
WHERE U.GENDER IS NOT NULL
GROUP BY YEAR(O.SALES_DATE),MONTH(O.SALES_DATE),U.GENDER
ORDER BY YEAR(O.SALES_DATE),MONTH(O.SALES_DATE),U.GENDER
회원수를 구하는문제에서 count 함수만써서 구매건수를 구하여 오답이었던 문제였다.
문제 더 꼼꼼히 읽어보자!