SIMPLE || EASY APPROACH || MySQL✔
Code

# Code
```mysql []
# Write your MySQL query statement below
SELECT ROUND(COUNT(DISTINCT player_id) / (SELECT COUNT(DISTINCT player_id) FROM Activity) , 2) AS fraction
FROM Activity 
WHERE(player_id , DATE_SUB(event_date , INTERVAL 1 DAY )) IN(
    SELECT player_id , MIN(event_date) AS first_login
    FROM Activity
    GROUP BY player_id
)
```
['Database', 'MySQL']