[SQL] 오프라인/온라인 판매 데이터 통합하기

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

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1. 해결방법

select 문 두개를 union all 문법을 이용해서 하나의 테이블로 합쳤다,

 

 

2. 정답코드

select DATE_FORMAT(A.SALES_DATE, "%Y-%m-%d") AS SALES_DATE, A.PRODUCT_ID, A.USER_ID, A.SALES_AMOUNT from ONLINE_SALE as A
where YEAR(A.SALES_DATE) = '2022' and MONTH(A.SALES_DATE) = '03'
union all
select DATE_FORMAT(B.SALES_DATE, "%Y-%m-%d") AS SALES_DATE, B.PRODUCT_ID, NULL as USER_ID, B.SALES_AMOUNT from  OFFLINE_SALE as B
where YEAR(B.SALES_DATE) = '2022' and MONTH(B.SALES_DATE) = '03'
order by SALES_DATE asc, PRODUCT_ID asc, USER_ID asc;