mysql 两个查询结果 并 运算

mysql 两个查询结果 并 运算

select column1 as one from a where id=1；
select column2 as two from b where id=1；

求 one two 运算

加法
select ( (select column1 as one from a where id=1)+(select column2 as two from b where id=1) )；