我有下面五个表，如果可能的话，我想使用一个mysql查询来显示每个国家、州、城市和地区的销售总额：
注意：如果州、市、区没有销售，那么我需要查询结果显示0或空格（即使特定州、市、区没有销售，也必须显示州、市、区名称）

+------------+----------+
|  country              |
+------------+----------+
| country_id | country  |
+------------+----------+
| 1          | country1 |
| 2          | country2 |
+------------+----------+

+----------------+--------+------------+
| state_province                       |
+----------------+--------+------------+
| state_id       | state  | country_id |
+----------------+--------+------------+
| 1              | state1 | 1          |
| 2              | state1 | 2          |
| 3              | state2 | 2          |
| 4              | state2 | 1          |
+----------------+--------+------------+

+---------+-------+----------+
|  city                      |
+---------+-------+----------+
| city_id | city  | state_id |
+---------+-------+----------+
| 1       | city1 | 1        |
| 2       | city2 | 1        |
| 3       | city1 | 3        |
| 4       | city2 | 3        |
| 5       | city1 | 4        |
| 6       | city2 | 4        |
+---------+-------+----------+

请注意，country（country\u id=2）中的state（state\u id=2）在上表中没有城市。

+-------------+-----------+---------+
|  district                         |
+-------------+-----------+---------+
| district_id | district  | city_id |
+-------------+-----------+---------+
| 1           | district1 | 1       |
| 2           | district2 | 1       |
| 3           | district1 | 2       |
| 4           | district2 | 2       |
| 5           | district1 | 4       |
| 6           | district2 | 4       |
| 7           | district1 | 5       |
| 8           | district1 | 6       |
+-------------+-----------+---------+

+----------+------------+----------+---------+-------------+--------+
|  sales                                                            |
+----------+------------+----------+---------+-------------+--------+
| sales_id | country_id | state_id | city_id | district_id | amount |
+----------+------------+----------+---------+-------------+--------+
| 1        | 1          | 0        | 0       | 0           | 1000   |
| 2        | 1          | 0        | 0       | 0           | 2000   |
| 3        | 1          | 1        | 0       | 0           | 300    |
| 4        | 1          | 1        | 0       | 0           | 70     |
| 5        | 1          | 1        | 1       | 0           | 50     |
| 6        | 1          | 1        | 1       | 1           | 25     |
| 7        | 1          | 4        | 1       | 1           | 25     |
| 8        | 1          | 4        | 5       | 0           | 25     |
| 9        | 2          | 0        | 0       | 0           | 3000   |
| 10       | 2          | 0        | 0       | 0           | 500    |
| 11       | 2          | 3        | 0       | 0           | 300    |
| 12       | 2          | 3        | 4       | 6           | 70     |
+----------+------------+----------+---------+-------------+--------+

演示我当前的尝试
谢谢您