题解 | 查找在职员工自入职以来的薪水涨幅情况

SELECT s1.emp_no, (s1.salary - s2.salary)growth
FROM 
(SELECT emp_no, salary  -- 当前工资
FROM salaries
WHERE to_date = '9999-01-01')s1
JOIN
(SELECT s.emp_no, s.salary -- 入职工资
FROM salaries AS s JOIN employees AS e
ON e.emp_no = s.emp_no
AND e.hire_date = s.from_date)s2
ON s1.emp_no = s2.emp_no
ORDER BY growth;