[프로그래머스] - 오프라인/온라인 판매 데이터 통합하기

문제링크: https://school.programmers.co.kr/learn/courses/30/lessons/131537

프로그래머스

풀이

SELECT DATE_FORMAT(SALES_DATE,"%Y-%m-%d"), PRODUCT_ID, USER_ID, SALES_AMOUNT FROM 
(SELECT SALES_DATE, PRODUCT_ID, USER_ID, SALES_AMOUNT FROM 
(SELECT * FROM ONLINE_SALE WHERE SALES_DATE BETWEEN '2022-03-01' AND '2022-03-31') AS ONS
UNION
SELECT SALES_DATE, PRODUCT_ID, NULL as USER_ID, SALES_AMOUNT FROM 
(SELECT * FROM OFFLINE_SALE WHERE SALES_DATE BETWEEN '2022-03-01' AND '2022-03-31') AS OFS)
AS tot
ORDER BY tot.SALES_DATE, tot.PRODUCT_ID, tot.USER_ID