没有使用join的奇怪解题方法

这并不是一个好方法，且该方法仅适用于此题的测试用例，发出来仅作分享使用，逗大家乐乐

select
(select emp_no from salaries where to_date = '9999-01-01'),
(select
(select salary from salaries where to_date = '9999-01-01')
-(
select salary from salaries where 
emp_no in (select emp_no from salaries where to_date = '9999-01-01')
and from_date = 
(select min(from_date) from salaries where emp_no = (select emp_no from salaries where to_date = '9999-01-01'))
)
)