MySQL多列单查询

我有一个数据库，保存客户的数据。我需要知道我们在各个城市和国家有多少客户。我必须用一个查询来完成它

我的表是customers，我有city列和country列（都是varchar），其中包含关于它的信息

所需的查询输出应如下所示：

City | NumberOfCustomers | Country | NumberOfCustomers |
--------------------------------------------------------

谢谢

编辑以显示该查询的示例表和输出：

mysql> select * from location;
+-------+---------+
| city  | country |
+-------+---------+
| City1 | US      |
| City2 | US      |
| City2 | US      |
| City3 | CA      |
| City3 | CA      |
| City3 | JP      |
+-------+---------+
6 rows in set (0.00 sec)

mysql> select city, country, count(*) from location group by 1,2 with rollup;
+-------+---------+----------+
| city  | country | count(*) |
+-------+---------+----------+
| City1 | US      |        1 |
| City1 | NULL    |        1 |
| City2 | US      |        2 |
| City2 | NULL    |        2 |
| City3 | CA      |        2 |
| City3 | JP      |        1 |
| City3 | NULL    |        3 |
| NULL  | NULL    |        6 |
+-------+---------+----------+
8 rows in set (0.01 sec)

---

期望的输出很奇怪。不客气，“我必须用单次查询来完成”——这项要求背后有什么技术原因？@zerkms“因为我的老师告诉过我。”@Crontab：我打赌不是这样，而是类似于“因为一次查询比两次查询快”：-@zerkms你可能是对的MySQL是否支持带有的

@showdev-我更新了一个示例来说明mysql的“with”是如何实现的used@atxdba谢谢有没有办法把他们分组？像USA-36而不是USA-1在36行？@atxdba感谢编辑，看起来我很困惑。
mysql> select * from location;
+-------+---------+
| city  | country |
+-------+---------+
| City1 | US      |
| City2 | US      |
| City2 | US      |
| City3 | CA      |
| City3 | CA      |
| City3 | JP      |
+-------+---------+
6 rows in set (0.00 sec)

mysql> select city, country, count(*) from location group by 1,2 with rollup;
+-------+---------+----------+
| city  | country | count(*) |
+-------+---------+----------+
| City1 | US      |        1 |
| City1 | NULL    |        1 |
| City2 | US      |        2 |
| City2 | NULL    |        2 |
| City3 | CA      |        2 |
| City3 | JP      |        1 |
| City3 | NULL    |        3 |
| NULL  | NULL    |        6 |
+-------+---------+----------+
8 rows in set (0.01 sec)