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 - e1.salary ) AS growth 
FROM# 查询当前工资
( SELECT emp_no, salary FROM salaries WHERE to_date = '9999-01-01' ) AS s1 # 内连接2次查询结果
INNER JOIN # 查询入职时候的工资
(
    SELECT
        s.emp_no,
        s.salary 
    FROM
        salaries AS s
        INNER JOIN employees AS e ON s.emp_no = e.emp_no 
        AND s.from_date = e.hire_date 
    WHERE
        #查询还在职的员工的员工
    s.emp_no IN ( SELECT emp_no FROM salaries WHERE to_date = '9999-01-01' )) AS e1 ON s1.emp_no = e1.emp_no 
ORDER BY
    growth