[SELECT] 오프라인/온라인 판매 데이터 통합하기

문제 설명

 

문제 

 

예시

 

해결

SELECT DATE_FORMAT(SALES_DATE, "%Y-%m-%d") SALES_DATE, PRODUCT_ID, USER_ID, SALES_AMOUNT
FROM ONLINE_SALE 
WHERE SALES_DATE BETWEEN '2022-03-01' AND '2022-03-31'
UNION ALL
SELECT DATE_FORMAT(SALES_DATE, "%Y-%m-%d") SALES_DATE, PRODUCT_ID, NULL USER_ID, SALES_AMOUNT
FROM OFFLINE_SALE 
WHERE SALES_DATE BETWEEN '2022-03-01' AND '2022-03-31'
ORDER BY SALES_DATE, PRODUCT_ID, USER_ID;