DecoderReloaded's questions

我有两张桌子：

1. things:

   +------+----------------+------------+
   | id   | current_status | created_at |
   +------+----------------+------------+
   | 7770 | active         | 2016-08-09 |
   +------+----------------+------------+
   

2. thing_status_tract:

   +----------+-------------+-----------+---------------------+
   | thing_id | status_from | status_to | changed_at          |
   +----------+-------------+-----------+---------------------+
   |     7770 | incomplete  | inactive  | 2016-08-09 16:26:22 |
   |     7770 | inactive    | active    | 2016-08-10 12:31:04 |
   +----------+-------------+-----------+---------------------+
   

我需要以下形式的数据。此表具有特定状态及其相应的开始和结束时间戳thing_id：

+----------+-------------+---------------------+---------------------+
| thing_id | status      | status_start_date   | status_end_date     |
+----------+-------------+---------------------+---------------------+
|     7770 | incomplete  | 2016-08-09 00:00:00 | 2016-08-09 16:26:22 |
|     7770 | inactive    | 2016-08-09 16:26:22 | 2016-08-10 12:31:04 |
|     7770 | active      | 2016-08-10 12:31:04 | now()               |
+----------+-------------+---------------------+---------------------+

如何使用 SQL 查询来做到这一点？