题解 | #查找在职员工自入职以来的薪水涨幅情况#

select emp_no,sum(diff) growth
from(
    select emp_no,-salary diff
    from employees left join salaries using(emp_no)
    where from_date = hire_date and emp_no in (
        select emp_no
        from salaries
        where to_date = "9999-01-01"
    )
    union
    select emp_no,salary diff
    from employees left join salaries using(emp_no)
    where to_date = "9999-01-01"
)t
group by emp_no
order by growth