-- One-shot: devices.created_at on/after Sep 17 still +8h (missed by 14:00 cutoff).
-- Do not re-run the previous shift-old-datetimes script.

SET time_zone = '+08:00';
SET @from = '2026-09-17 00:00:00';

SELECT COUNT(*) AS n, MIN(created_at) AS mn, MAX(created_at) AS mx
  FROM devices
 WHERE created_at IS NOT NULL AND created_at >= @from;

UPDATE devices
   SET created_at = DATE_SUB(created_at, INTERVAL 8 HOUR)
 WHERE created_at IS NOT NULL AND created_at >= @from;

SELECT ROW_COUNT() AS created_at_updated;

SELECT id, device_id, created_at, updated_at
  FROM devices
 WHERE created_at IS NOT NULL
 ORDER BY created_at DESC
 LIMIT 5;