[리트코드/SQL] 20. User Activity for the Past 30 Days I (1141)

👉https://leetcode.com/problems/user-activity-for-the-past-30-days-i/?envType=study-plan&id=sql-i

User Activity for the Past 30 Days I - LeetCode

 

---

🤔 문제 분석

1) Write an SQL query to find the daily active user count for a period of 30 days ending 2019-07-27 inclusively. A user was active on someday if they made at least one activity on that day.

2) Return the result table in any order.

 

💡 풀이

SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
FROM Activity
WHERE activity_date > "2019-06-27" 
AND activity_date < "2019-07-28"
GROUP BY activity_date