User Activity for the Past 30 Days II — LeetCode 1142 Python Solution

Table: Activity +---------------+---------+ | 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').

+---------------+---------+
| 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.

import duckdb
import pandas as pd

def solution(activity: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("Activity", activity)
    return con.execute("""WITH
    T AS (
        SELECT
            COUNT(DISTINCT session_id) AS sessions
        FROM Activity
        WHERE activity_date <= '2019-07-27' AND DATEDIFF('2019-07-27', activity_date) < 30
        GROUP BY user_id
    )
SELECT IFNULL(ROUND(AVG(sessions), 2), 0) AS average_sessions_per_user
FROM T;""").df()