Using Subquery, easy to understand
\n\n# Code\n\n\nSELECT \n    ROUND(COUNT(*)::numeric / (SELECT COUNT(DISTINCT player_id) FROM Activity), 2) AS fraction\nFROM Activity\nWHERE (player_id, event_
\n\n# Code\n```\n\nSELECT \n    ROUND(COUNT(*)::numeric / (SELECT COUNT(DISTINCT player_id) FROM Activity), 2) AS fraction\nFROM Activity\nWHERE (player_id, event_date) IN (\n    SELECT\n        player_id,\n        MIN(event_date) + INTERVAL \'1 day\' AS event_date\n    FROM Activity\n    GROUP BY player_id\n);\n\n    \n```
['PostgreSQL']