Question

我想做一个嵌套聚合，我可以选择是否聚合嵌套平均聚合的最大值，最小值或平均值。

我希望我的结果如下所示:(类型，MAX或MIN或嵌套AVG的AVG）

当前我有一个嵌套聚合查询，它只返回一个类型的最大平均价格，但我似乎也无法选择与该最大值对应的类型。

考虑表游戏（gameID，gameName，流派，价格），忽略gameID和gameName。

我现在拥有的嵌套查询：

SELECT MAX(avggenreprice) AS maxavg
FROM    (
    SELECT genre as subgenre, AVG(price) as avggenreprice
    FROM games
    GROUP BY 
        subgenre
) AS sub;

此查询的示例结果：

|maxavg|

| 368.22|

我希望它看起来像这样

| genre | maxavg |

| Racer | 368.22 |

我试过了：

SELECT sub.subgenre, MAX(avggenreprice) AS maxavg
FROM    (
    SELECT genre as subgenre, AVG(price) as avggenreprice
    FROM games
    GROUP BY 
        subgenre
    ) AS sub
;

但这只是给我错误代码1140

Answer 1

select top 1  subgenre AS genre ,  AVG (price) As maxavg   from games  
group by  subgenre order  by AVG (price) desc

Answer 2

SELECT subgenre, avggenreprice AS maxavg
FROM    (
    SELECT genre as subgenre, AVG(price) as avggenreprice
    FROM games
    GROUP BY 
        subgenre
) AS sub 
ORDER BY avggenreprice DESC 
Limit 1;

当MySQL不确定如何处理聚合函数并且需要显式的GROUP BY子句时，会出现1140代码。见（MySQL #1140 - Mixing of GROUP columns）。

对于您的案例，最简单的解决方案是使用排序DESC和限制1子句替换聚合函数max。

Answer 3

只需使用ORDER BY和LIMIT即可。子查询不是必需的：

SELECT genre as subgenre, AVG(price) as avggenreprice
FROM games
GROUP BY subgenre
ORDER BY avggenreprice DESC
LIMIT 1;

如何显示列名称和嵌套聚合结果

3 个答案: