没有用到第一个表好像也可以,解法如下:
select t1.emp_no,(t2.x-t1.n) growth from (select emp_no,min(from_date),min(salary) n from salaries group by emp_no) t1 join (select emp_no,max(salary) x from salaries where to_date='9999-01-01' group by emp_no) t2 on t1.emp_no=t2.emp_no order by growth