Solution 1
SELECT player_id, device_id
FROM Activity
WHERE (player_id, event_date) IN (
SELECT player_id, MIN(event_date)
FROM Activity
GROUP BY player_id
);Last updated
SELECT player_id, device_id
FROM Activity
WHERE (player_id, event_date) IN (
SELECT player_id, MIN(event_date)
FROM Activity
GROUP BY player_id
);Last updated