Easy solution to understand
\n\n# Code\nmysql []\n# Write your MySQL query statement below\nSELECT ROUND( COUNT( Distinct player_id) / (SELECT COUNT( DISTINCT player_id) FROM Activity) , 2
\n\n# Code\n```mysql []\n# Write your MySQL query statement below\nSELECT ROUND( COUNT( Distinct player_id) / (SELECT COUNT( DISTINCT player_id) FROM Activity) , 2 ) AS fraction\n\nFROM Activity A\n\nWHERE (player_id , DATE_SUB( event_date , INTERVAL 1 DAY ) ) IN (\n\n    SELECT player_id , MIN(event_date) AS first FROM Activity GROUP BY player_id\n\n)\n \n```
['MySQL']