Last updated on January 22nd, 2025 at 11:19 pm

Here, we see the User Activity for the Past 30 Days I LeetCode Solution. This Leetcode problem is solved using MySQL and Pandas.

List of all LeetCode Solution

Level of Question

Easy

User Activity for the Past 30 Days I LeetCode Solution

1. Problem Statement

Column Name	Type
user_id	int
session_id	int
activity_date	date
activity_type	enum

This table may have duplicate rows.
The activity_type column is an ENUM (category) of type (‘open_session’, ‘end_session’, ‘scroll_down’, ‘send_message’). The table shows the user activities for a social media website. Note that each session belongs to exactly one user.

Write a solution 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.

Return the result table in any order.

The result format is in the following example.

Example 1:
Input:

user_id	session_id	activity_date	activity_type
1	1	2019-07-20	open_session
1	1	2019-07-20	scroll_down
1	1	2019-07-20	end_session
2	4	2019-07-20	open_session
2	4	2019-07-21	send_message
2	4	2019-07-21	end_session
3	2	2019-07-21	open_session
3	2	2019-07-21	send_message
3	2	2019-07-21	end_session
4	3	2019-06-25	open_session
4	3	2019-06-25	end_session

Output:

day	active_users
2019-07-20	2
2019-07-21	2

Explanation: Note that we do not care about days with zero active users.

2. Code Implementation in Different Languages

2.1 User Activity for the Past 30 Days I MySQL

select 
  activity_date as day, 
  count(distinct user_id) as active_users 
from 
  Activity 
where 
  activity_date between '2019-06-28' 
  and '2019-07-27' 
group by 
  day;