如何对MySQL中的多个子查询行求和?

以下是一种适合您的方法:

SELECT SUM(column_alias)
FROM (select ... as column_alias from ...) as table_alias

下面是一个具体的虚拟示例来展示该方法的实际效果:

select sum(int_val) 
from (
  select 1 as int_val 
  union
  select 2 as int_val 
  union 
  select 3 as int_val
) as sub;

你就不能做个聚合吗 在内部

SELECT
    (SELECT SUM(...) ...) AS total,
    ...

(未经测试!)