如何退回按城市销售的最大产品？答案

【问题标题】：How I can return the max product that was sold by city?如何退回按城市销售的最大产品？
【发布时间】：2015-09-29 06:29:26
【问题描述】：

我有按城市销售的产品如何退回按城市销售的最大产品？？

这是我的查询：

我对每种产品的数量进行了求和，以获得按产品数量的单一值。

select
product,
sum(qty_city_o) as qty_o,
sum(qty_city_t) as qty_t,
sum(qty_city_th) as qty_th
FROM products
GROUP BY product

【问题讨论】：

使用max 而不是sum
@vkp 同一种产品可以多次销售，这就是为什么我要按产品求和 f 以返回单个数量值。
我没有看到任何地方提到的city 列。
qty_city_o,qty_city_t,qty_city_th
您能否提供一些示例数据以及预期结果？就目前而言，尚不清楚您实际想要实现的目标。

标签： mysql sql

【解决方案1】：

您必须将每个城市作为单独的查询进行。比如：

SELECT qty_city_o, COUNT(product) FROM products GROUP BY qty_city_o ORDER BY COUNT(product) DESC LIMIT 1

【讨论】：

【解决方案2】：

这应该为您提供每个城市的最大销售产品：

SELECT 'city_o', A.* FROM (SELECT 
    product, productcount
FROM
    (SELECT 
        product, COUNT(product) productcount
    FROM
        products
    WHERE
        qty_city_o > 0
    GROUP BY product) B
ORDER BY productcount DESC
LIMIT 1 ) A
UNION ALL
SELECT 'city_t', A.* FROM (SELECT 
    product, productcount
FROM
    (SELECT 
        product, COUNT(product) productcount
    FROM
        products
    WHERE
        qty_city_t > 0
    GROUP BY product) B
ORDER BY productcount DESC
LIMIT 1 ) A
UNION ALL
SELECT 'city_th', A.* FROM (SELECT 
    product, productcount
FROM
    (SELECT 
        product, COUNT(product) productcount
    FROM
        products
    WHERE
        qty_city_th > 0
    GROUP BY product) B
ORDER BY productcount DESC
LIMIT 1) A;

【讨论】：