orders（流量订单表）
| Name | Type | Relation With | Description |
|---|---|---|---|
| order_id | Number | 订单号 | |
| odrer_status | Enumeration | 订单状态 pending, paid, unshipped, shipped, canceled | |
| amount | Float | 订单金额 | |
| pay_time | Date | 支付时间 | |
| type | Enumeration | 订单类型 | |
| order_items | Object | 订单详情，不同的订单以对象形式存储 | |
| user | Relation | User |