코딩 테스트 - 년, 월, 성별 별 상품 구매 회원 수 구하기

참조 : https://jmi7313.tistory.com/12

fm 안 붙여도 정답 처리 되기는 하지만...

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

--Oracle

SELECT
    YEAR,
    TO_NUMBER(MONTH) AS MONTH,
    GENDER,
    COUNT(
    DISTINCT
    USER_ID
    ) AS USERS
FROM(
    SELECT
    TO_CHAR(SALES_DATE,'YYYY') AS YEAR,
    TO_CHAR(SALES_DATE,'MM') AS MONTH,
    GENDER,
    USER_INFO.USER_ID
    FROM
    USER_INFO,ONLINE_SALE
    WHERE
    USER_INFO.USER_ID = ONLINE_SALE.USER_ID
    AND
    GENDER IS NOT NULL
    )
GROUP BY
    YEAR, MONTH, GENDER
ORDER BY
    YEAR ,MONTH,GENDER;