可以说我有下表：
Countries --------------------------- | ID | Country Name | --------------------------- | 1 | Greece | | 2 | Italy | | 3 | Spain | --------------------------- Cities --------------------------- | ID | City | --------------------------- | 1 | Athens | | 2 | Patra | | 3 | Rome | | 4 | Venice | --------------------------- Countries & Cities -------------------- | ID | Cntr | City | -------------------- | 1 | 1 | 2 | | 2 | 1 | 1 | | 3 | 2 | 3 | --------------------
现在，如何运行MySQL查询，该查询将基于“国家/城市”表返回国家和城市总数？
在示例中返回：
--------------------------- | Cities | Country | --------------------------- | 2 | Greece | | 1 | Italy | ---------------------------
试试看：
SELECT COUNT(cs.City) as Cities, cn.name as Country FROM countries cn INNER JOIN country_city cs ON cs.Cntr = cn.id GROUP BY cn.name
输出：
2 | Greece 1 | Italy
