题解 | #查找在职员工自入职以来的薪水涨幅情况#

select t1.emp_no,t1.salary-t2.salary growth from
(
#在职员工现在的工资表
    select a.emp_no,b.salary 
    from employees a 
    left join salaries b 
    on a.emp_no=b.emp_no 
    where b.to_date='9999-01-01'
) t1 join
(
#在职员工入职的工资表
    select a.emp_no,b.salary 
    from employees a 
    left join salaries b 
    on a.emp_no=b.emp_no 
    and a.hire_date=b.from_date 
) t2
on t1.emp_no=t2.emp_no
order by growth
;