查找员工编号emp_no为10001其自入职以来的薪水salary涨幅值growth
CREATE TABLE salaries (
emp_no int(11) NOT NULL,
salary int(11) NOT NULL,
from_date date NOT NULL,
to_date date NOT NULL,
PRIMARY KEY (emp_no,from_date));
–select 也可以这么用：将to_date 最大值（当前）的薪水-to_date 最小值（入职当天）的薪水拿到
select
((select salary
from salaries
where emp_no = 10001
order by to_date desc
limit 0,1)
-
(select salary
from salaries
where emp_no = 10001
order by to_date asc
limit 0,1))
as growth;
