diff --git a/scripts/shift-old-datetimes-minus-8h.sql b/scripts/shift-old-datetimes-minus-8h.sql
index abd3bf6..193cb6d 100644
--- a/scripts/shift-old-datetimes-minus-8h.sql
+++ b/scripts/shift-old-datetimes-minus-8h.sql
@@ -1,5 +1,5 @@
--- Only devices.* times. Dashboard / daily-report device counts use created_at
--- (and updated_at for「活跃」). Do not touch photos / visits / other tables.
+-- Only devices.created_at / updated_at. first_seen_at / last_seen_at
+-- were dropped (see 2026_08_04_000002_simplify_devices_columns).
 --
 -- 1) 备份 devices
 -- 2) 把 @cutoff 改成切时区那一刻
@@ -12,11 +12,7 @@ SET @cutoff = '2026-09-16 14:00:00';  -- TODO: 改成实际切时区的时间
 SELECT '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 'updated_at', COUNT(*), MIN(updated_at), MAX(updated_at)
-  FROM devices WHERE updated_at IS NOT NULL AND updated_at < @cutoff
-UNION ALL SELECT 'first_seen_at', COUNT(*), MIN(first_seen_at), MAX(first_seen_at)
-  FROM devices WHERE first_seen_at IS NOT NULL AND first_seen_at < @cutoff
-UNION ALL SELECT 'last_seen_at', COUNT(*), MIN(last_seen_at), MAX(last_seen_at)
-  FROM devices WHERE last_seen_at IS NOT NULL AND last_seen_at < @cutoff;
+  FROM devices WHERE updated_at IS NOT NULL AND updated_at < @cutoff;
 
 START TRANSACTION;
 
@@ -24,10 +20,6 @@ UPDATE devices SET created_at = DATE_SUB(created_at, INTERVAL 8 HOUR)
  WHERE created_at IS NOT NULL AND created_at < @cutoff;
 UPDATE devices SET updated_at = DATE_SUB(updated_at, INTERVAL 8 HOUR)
  WHERE updated_at IS NOT NULL AND updated_at < @cutoff;
-UPDATE devices SET first_seen_at = DATE_SUB(first_seen_at, INTERVAL 8 HOUR)
- WHERE first_seen_at IS NOT NULL AND first_seen_at < @cutoff;
-UPDATE devices SET last_seen_at = DATE_SUB(last_seen_at, INTERVAL 8 HOUR)
- WHERE last_seen_at IS NOT NULL AND last_seen_at < @cutoff;
 
 -- 后台看一台改时区前的设备，时间对了再 COMMIT
 COMMIT;