Question

我想从以下select中选择具有最大值的行，但子查询（select max(result.Sum) from result）中的结果表名称是错误的：

select *
from 
(select sum(Rooms.n_seats) as 'Sum', DepKinds.title
from Rooms join Departments on Rooms.department = Departments.id
join DepKinds on Departments.kind = DepKinds.id group by DepKinds.title) result where result.Sum = (select max(result.Sum) from result);

那么如何为这些总和选择最大总和和标题？

Answer 1

在子查询中无法使用result后面的FROM别名。尝试使用HAVING。

select sum(Rooms.n_seats) as 'Sum', DepKinds.title
from Rooms 
join Departments on Rooms.department = Departments.id
join DepKinds on Departments.kind = DepKinds.id 
group by DepKinds.title
having sum(Rooms.n_seats) >= all
(
   select sum(Rooms.n_seats) 
   from Rooms 
   join Departments on Rooms.department = Departments.id
   join DepKinds on Departments.kind = DepKinds.id 
   group by DepKinds.title   
)

这将返回具有最多席位数的所有 DepKinds.title。

从select result中选择具有最大值的行

1 个答案: