drop table if exists `employees` ;
drop table if exists `salaries` ;
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));
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`));
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','2001-06-22');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1999-08-03');

INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22');
INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01');
INSERT INTO salaries VALUES(10002,72527,'1999-08-03','2000-08-02');
INSERT INTO salaries VALUES(10002,72527,'2000-08-02','2001-08-02');

--SQL21 查找在职员工自入职以来的薪水涨幅情况

select ss.emp_no,ss.salary-rr.salary growth
from
(select emp_no,salary
from salaries ss where to_date ='9999-01-01') ss
inner join
(select a.emp_no,salary,from_date from salaries s join
(select emp_no,min(from_date) mindate from salaries group by emp_no) a
on s.emp_no=a.emp_no and s.from_date = a.mindate) rr
on ss.emp_no=rr.emp_no order by growth;

select b.emp_no,(b.salary-a.salary) as growth
from
(select e.emp_no,s.salary
from employees e left join salaries s on e.emp_no=s.emp_no
and e.hire_date=s.from_date)a -- 入职工资表
inner join
(select e.emp_no,s.salary
from employees e left join salaries s on e.emp_no=s.emp_no
where s.to_date='9999-01-01')b -- 现在工资表
on a.emp_no=b.emp_no
order by growth