DB2如何从两个不同的表中对两列进行求和

Question

Select sum(amt) as totalA from tableA where id>10;
Select sum(amount) as totalB from tableB where people = 'JOSH';

如果目标是sum(totalA + totalB)？

，最好的方法是什么？

Answer 1

select sum(total) from
(
    select sum(amt) as total from tableA where id>10
    union all
    select sum(amount) from tableB where people = 'JOSH'
) as q