mysql - 错误 1140 (42000) 在没有 GROUP BY 的聚合查询中，表达式 #1

Question

我的问题来自https://www.hackerrank.com/challenges/earnings-of-employees/problem

下面是输入数据:

该问题要求找出最大收入(月数 * 薪水)和具有最大收入的行的总数。

我的尝试是:

select distinct salary*months, count(*)
from employee
where salary*months = (select max(salary*months) from employee)

这给了我错误信息:

ERROR 1140 (42000) at line 6: In aggregated query without GROUP BY, expression #1 of SELECT list contains nonaggregated column 'run_byli4vf7yqz.employee.salary'; this is incompatible with sql_mode=only_full_group_by`

对我失败的原因有什么建议吗？

Answer 1

不要使用select distinct:

select (e.salary * e.months), count(*)
from employee e
where (e.salary * e.months) = (select max(e2.salary * e2.months)
                               from employee e2
                              )
group by (e.salary * e.months);

信息很清楚。你有 count(*) 所以你的查询是一个聚合查询。但是，您有一个未聚合的列，因此 MySQL 很困惑:您是否想要聚合？因此错误。

你也可以这样写:

select (e.salary * e.months), count(*)
from employee e
group by (e.salary * e.months)
order by (e.salary * e.months) desc
limit 1;