先找出员工刚入职时候的工资 , 利用入职时间连表查询
找出员工现在的工资
将1. 2.得出的子表 进行连表查询
SELECT s1.emp_no, s1.salary - s2.salary growth FROM ( SELECT emp_no, salary FROM salaries WHERE to_date = '9999-01-01' ) s1 JOIN (SELECT e.emp_no, s.salary FROM employees e JOIN salaries s ON e.emp_no = s.emp_no WHERE e.hire_date = s.from_date ) s2 on s1.emp_no = s2.emp_no ORDER BY growth ASC;