diff --git a/sql/cleanup_demo_data.sql b/sql/cleanup_demo_data.sql
new file mode 100644
index 0000000..def6516
--- /dev/null
+++ b/sql/cleanup_demo_data.sql
@@ -0,0 +1,85 @@
+-- 清理演示过程数据：秒杀活动、秒杀订单、admin 前台订单/拼团/评价/收藏/通知数据
+-- 适用于已导入 flash_sale_db.sql 的 MySQL 数据库。
+
+SET @admin_user_id := (SELECT id
+                       FROM users
+                       WHERE username = 'admin'
+                       LIMIT 1);
+
+CREATE TEMPORARY TABLE IF NOT EXISTS cleanup_group_ids
+(
+    id BIGINT PRIMARY KEY
+) ENGINE = Memory;
+
+CREATE TEMPORARY TABLE IF NOT EXISTS cleanup_order_ids
+(
+    id BIGINT PRIMARY KEY
+) ENGINE = Memory;
+
+TRUNCATE TABLE cleanup_group_ids;
+TRUNCATE TABLE cleanup_order_ids;
+
+INSERT IGNORE INTO cleanup_group_ids (id)
+SELECT id
+FROM group_buying_group
+WHERE leader_user_id = @admin_user_id;
+
+INSERT IGNORE INTO cleanup_order_ids (id)
+SELECT id
+FROM orders
+WHERE order_type = 2
+   OR flash_sale_id IS NOT NULL
+   OR user_id = @admin_user_id
+   OR group_buying_group_id IN (SELECT id FROM cleanup_group_ids);
+
+DELETE n
+FROM notifications n
+WHERE n.user_id = @admin_user_id
+   OR n.link IN (SELECT CONCAT('/order/', id)
+                 FROM cleanup_order_ids);
+
+DELETE pr
+FROM product_reviews pr
+WHERE pr.user_id = @admin_user_id
+   OR pr.order_id IN (SELECT id FROM cleanup_order_ids);
+
+DELETE r
+FROM order_returns r
+WHERE r.user_id = @admin_user_id
+   OR r.order_id IN (SELECT id FROM cleanup_order_ids);
+
+DELETE oi
+FROM order_items oi
+WHERE oi.order_id IN (SELECT id FROM cleanup_order_ids);
+
+DELETE gbm
+FROM group_buying_member gbm
+WHERE gbm.user_id = @admin_user_id
+   OR gbm.order_id IN (SELECT id FROM cleanup_order_ids)
+   OR gbm.group_id IN (SELECT id FROM cleanup_group_ids);
+
+DELETE o
+FROM orders o
+WHERE o.id IN (SELECT id FROM cleanup_order_ids);
+
+DELETE g
+FROM group_buying_group g
+WHERE g.id IN (SELECT id FROM cleanup_group_ids);
+
+DELETE uf
+FROM user_favorites uf
+WHERE uf.user_id = @admin_user_id;
+
+DELETE ua
+FROM user_addresses ua
+WHERE ua.user_id = @admin_user_id;
+
+DELETE
+FROM flash_sales;
+
+UPDATE users
+SET role = 'ADMIN'
+WHERE username = 'admin';
+
+DROP TEMPORARY TABLE IF EXISTS cleanup_order_ids;
+DROP TEMPORARY TABLE IF EXISTS cleanup_group_ids;