MySQL Solution
Code\n\n# Write your MySQL query statement below\nWITH \n    a2 AS (SELECT player_id, MIN(event_date) AS min_date FROM Activity\n    GROUP BY player_id)\n\nSELE
# Code\n```\n# Write your MySQL query statement below\nWITH \n    a2 AS (SELECT player_id, MIN(event_date) AS min_date FROM Activity\n    GROUP BY player_id)\n\nSELECT ROUND(COUNT(a1.player_id) / (SELECT COUNT(player_id) FROM a2), 2) AS fraction\nFROM Activity a1 JOIN a2 ON a1.player_id = a2.player_id AND a2.min_date = DATE_SUB(a1.event_date, INTERVAL 1 DAY);\n```
['MySQL']