-- Only devices.created_at / updated_at.
-- 用 mysql -uroot -p -t -vv coruna < 本文件 才会打印行数。
-- 已成功跑过就不要再跑（会再减 8 小时）。
-- 改完后：php artisan coruna:daily-stats --all

SET time_zone = '+08:00';
SET @cutoff = '2026-09-16 14:00:00';  -- TODO: 改成实际切时区的时间

SHOW COLUMNS FROM devices LIKE '%_at';

SELECT 'preview' AS step, 'created_at' AS col, COUNT(*) AS n,
       MIN(created_at) AS mn, MAX(created_at) AS mx
  FROM devices WHERE created_at IS NOT NULL AND created_at < @cutoff
UNION ALL
SELECT 'preview', 'updated_at', COUNT(*), MIN(updated_at), MAX(updated_at)
  FROM devices WHERE updated_at IS NOT NULL AND updated_at < @cutoff;

START TRANSACTION;

UPDATE devices SET created_at = DATE_SUB(created_at, INTERVAL 8 HOUR)
 WHERE created_at IS NOT NULL AND created_at < @cutoff;
SELECT ROW_COUNT() AS created_at_updated;

UPDATE devices SET updated_at = DATE_SUB(updated_at, INTERVAL 8 HOUR)
 WHERE updated_at IS NOT NULL AND updated_at < @cutoff;
SELECT ROW_COUNT() AS updated_at_updated;

SELECT id, device_id, created_at, updated_at
  FROM devices
 WHERE created_at IS NOT NULL
 ORDER BY id ASC
 LIMIT 3;

COMMIT;