经典SQL题库

1、查找员工编号emp_now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`));

解题思路：巧妙使用max和min。

select (max(salary)-min(salary)) as groeth from salaries
where emp_no='10001'

2、

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_no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`));

解题思路：

先用内连接构造两张当前薪水和入职薪水表，然后再内连接这两张表，筛选出emp_no和growth

select currentSalary.emp_no,(currentSalary.salary-beginSalary.salary) as growth

from (select e.emp_no,s.salary

      from employees as e inner join salaries as s

      on e.emp_no=s.emp_no where s.to_date='9999-01-01') as currentSalary

inner join(select e.emp_no,s.salary

      from employees as e inner join salaries as s

      on e.emp_no=s.emp_no where s.from_date=e.hire_date) as beginSalary

on currentSalary.emp_no=beginSalary.emp_no

order by growth