SQL 문제 22 - User Activity for the Past 30 Days I LeetCode 1141

SQL 문제 22 - User Activity for the Past 30 Days I LeetCode 1141 User Activity for the Past 30 Days I 풀이 -- ORACLE SELECT TO_CHAR(ACTIVITY_DATE,'YYYY-MM-DD') AS DAY , COUNT(DISTINCT USER_ID) AS ACTIVE_USERS FROM ACTIVITY WHERE ACTIVITY_DATE < '2019-07-27' AND TO_DATE('2019-07-27','YYYY-MM-DD') - ACTIVITY_DATE < 30 GROUP BY ACTIVITY_DATE -- MYSQL SELECT ACTIVITY_DATE AS DAY , COUNT(DISTINCT USER_ID) AS ACTIVE_USERS FROM ACTIVITY WHERE ACTIVITY_DATE < '2019-07-27' AND DATEDIFF('2019-07-27',ACTIVITY_...