题目描述
查找所有员工自入职以来的薪水涨幅情况,给出员工编号emp_noy以及其对应的薪水涨幅growth,并按照growth进行升序
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`));
解题方案
本题的思路就在于分而治之,将入职薪资表和当前薪资表分别求得再进行关联,而入职工资就是employees表中的hire_date对应的日期再与salaries表关联可以得到;当前薪资可以通过日期为’9999-01-01’当做条件即可。
select s1.emp_no,(salary - old_salary) as growth
from (
select emp_no ,salary
from salaries
where to_date='9999-01-01'
) as s1
inner join (
select e.emp_no , salary as old_salary
from employees as e
left join
salaries as s
on e.emp_no = s.emp_no
and e.hire_date = s.from_date
)as f
on s1.emp_no = f.emp_no
order by growth