题解 | #构建两张临时表#

select
    b.emp_no,
    (b.salary - a.salary) growth
from
    (
        select
            e.emp_no,
            s.salary
        from
            employees e
        left join salaries s on e.emp_no = s.emp_no
        where s.to_date = '9999-01-01'
    ) b
left join (
        select
            e.emp_no,
            s.salary
        from
            employees e
        left join salaries s on e.emp_no = s.emp_no
        where e.hire_date = s.from_date
    ) a
on a.emp_no = b.emp_no
order by growth

本题通过入职和 9999-01-01 两个时间段分别筛选出刚入职和现在的工资表，最后通过现在的工资表 left join 入职工资表即可得题解。