选择最大列的值不会提供所需的结果

Question

有一个名为cities的表，看起来像这样：

id | city | population | year

我只需要：

对于每个城市，选择最大人口数量和最大人口数量。首选

是没有嵌套查询的解决方案

所以我尝试了这个：

SELECT `city`, MAX(`year`), MAX(`population`) FROM `cities` GROUP BY `city`

但它给出了错误的结果。我做错了什么？

Answer 1

首先，你必须采取超过你需要的最大人口数量。试试这个：

SELECT C.city, max(C2.year), C.MAX_population
FROM 
(SELECT city, MAX(population) AS MAX_population FROM cities GROUP BY city) C
JOIN cities C2 on C2.city = C.city and C2.population = C.MAX_population
GROUP BY C.city, C.MAX_population