SQL 子查询根据另一列的最大平均值显示一列的分组值

Question

我正在尝试根据 community_area_name 计算安全评分的最大平均值。我可以通过查询来做到这一点：

SELECT  max(average_safty) as maximum from (select community_area_name, AVG(safety_score) as average_safty from CHICAGO_PUBLIC_SCHOOLS group by community_area_name) ;

但现在我想为结果显示 community_area_name。我试过了：

SELECT  max(average_safty) as maximum, community_area_name from(select community_area_name, AVG(safety_score) as average_safty from CHICAGO_PUBLIC_SCHOOLS group by community_area_name) ;

但是我得到一个错误，因为它需要被分组。当我像这样分组时：

%sql SELECT  max(average_safty) as maximum, community_area_name from (select community_area_name, AVG(safety_score) as average_safty from CHICAGO_PUBLIC_SCHOOLS group by community_area_name) group by community_area_name ;

结果是每个 community_area_name 的所有平均值的列表，而不仅仅是最大平均值。

我如何得到如下结果？：

|community_area_name |最大|

地区名称 |最高平均值 |

Answer 1

使用order by 和fetch 子句：

select community_area_name, avg(safety_score) as average_safety
from CHICAGO_PUBLIC_SCHOOLS
group by community_area_name
order by average_safety desc
fetch first 1 row only;