SQL20 - 查找员工编号emp_now为10001其自入职以来的薪水salary涨幅值growth

题目描述：

查找员工编号emp_no为10001其自入职以来的薪水salary涨幅(总共涨了多少)growth(可能有多次涨薪，没有降薪)

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`));

 

难易程度：

简单

 

解答：

select a.salary-b.salary as 'growth'
from 
(select emp_no,salary from salaries where to_date = '9999-01-01' and emp_no = '10001') a left join
(select emp_no,min(to_date),salary from salaries where emp_no = '10001') b
on a.emp_no = b.emp_no