MySQL 从三个表中选择 [关闭]

Question

我需要编写查询以获取按专业划分的最大汇票的国家/地区。主表为：used_money

我有 3 张桌子：used_money、users、groups

我无法在此处发布图片：

我需要得到这样的结果：

Luxembourg    Hacker 200
Albania       Hacker 120
United States Boss    55

Answer 1

这样的？

查询：

SELECT country, profession, MAX(money) AS money 
FROM
(   SELECT u.country, g.profession, SUM(um.money) AS money
    FROM user_money um
    JOIN users u ON u.id = um.user_id
    JOIN groups g ON g.id = um.group_id
    GROUP BY g.profession, u.country
    ORDER BY um.money DESC
) t
GROUP BY country
ORDER BY money DESC

SEE DEMO

输出：

+---------------+------------+-------+
| country       | profession | money |
+---------------+------------+-------+
| Luxembourg    | Hacker     |  200  |
| Albania       | Hacker     |  120  |
| United States | Boss       |  55   |
+---------------+------------+-------+