题解 | #查找在职员工自入职以来的薪水涨幅情况#

不使用employess表

select first_sal.emp_no, (salaries.salary - first_sal.salary) as  growth
from
    (select salaries.emp_no,salary
    from (
        select emp_no,min(to_date) as to_date
        from salaries
        group by emp_no
    ) as first_sal_date
    join salaries
    on salaries.emp_no = first_sal_date.emp_no
    and salaries.to_date = first_sal_date.to_date
    ) as first_sal
join salaries
on salaries.emp_no = first_sal.emp_no
and salaries.to_date = "9999-01-01"
order by growth;