题解 | #查找在职员工自入职以来的薪水涨幅情况#

入职日对应的salary联合1，2表查，当前在职员工的薪水从2表查，减去即为涨薪值

select a.emp_no,b.salary-a.salary growth
from(
    select a.emp_no,salary
    from employees a,salaries b
    where a.emp_no=b.emp_no and a.hire_date=b.from_date
)a,(
    select emp_no,salary
    from salaries 
    where to_date='9999-01-01'
)b
where a.emp_no=b.emp_no
order by growth asc