[MySQL] 오프라인/온라인 판매 데이터 통합하기(프로그래머스)

SELECT DATE_FORMAT(SALES_DATE,"%Y-%m-%d") SALES_DATE
     , PRODUCT_ID
     , USER_ID
     , SALES_AMOUNT
FROM ONLINE_SALE
WHERE SALES_DATE >= '2022-03-01' and SALES_DATE < '2022-04-01'

UNION

SELECT DATE_FORMAT(SALES_DATE,"%Y-%m-%d") SALES_DATE
     , PRODUCT_ID
     , NULL AS USER_ID
     , SALES_AMOUNT
FROM OFFLINE_SALE 
WHERE SALES_DATE >= '2022-03-01' and SALES_DATE < '2022-04-01'
    
ORDER BY SALES_DATE , PRODUCT_ID , USER_ID