1、查询每个员工入职的薪水
select a.emp_no,a.salary as min_salary from salaries as a join employees as b on a.emp_no=b.emp_no where b.hire_date=a.from_date2、查询每个员工当前的薪水
select emp_no,salary as max_salary from salaries where to_date='9999-01-01'3、1表和2表右连接(即为在职员工),查询薪水涨幅值
select c.emp_no,d.max_salary-c.min_salary as growth from (select a.emp_no,a.salary as min_salary from salaries as a join employees as b on a.emp_no=b.emp_no where b.hire_date=a.from_date) as c right join (select emp_no,salary as max_salary from salaries where to_date='9999-01-01') as d on c.emp_no=d.emp_no order by growth;