題目地址
https://www.nowcoder.com/activity/oj

6.查找所有員工入職時候的薪水情況，給出emp_no以及salary， 并按照emp_no進(jìn)行逆序
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));

這題存在坑點(diǎn)，一個人的工資記錄可能不止一個，存在漲工資的可能
這里利用from_date和hire_date來確定入職時的工資

select t1.emp_no,salary 
from employees t1
inner join salaries t2
on t1.emp_no=t2.emp_no and t1.hire_date=t2.from_date
order by t1.emp_no desc;

7.題目描述
查找薪水漲幅超過15次的員工號emp_no以及其對應(yīng)的漲幅次數(shù)t
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));

按工號聚合后計算工資記錄數(shù)，大于15的算一條

select emp_no, count(salary) as t 
from salaries 
group by emp_no 
having t > 15;

8.題目描述
找出所有員工當(dāng)前(to_date='9999-01-01')具體的薪水salary情況，對于相同的薪水只顯示一次,并按照逆序顯示
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 distinct salary 
from salaries 
where to_date = '9999-01-01' 
order by salary desc;

9.題目描述
獲取所有部門當(dāng)前manager的當(dāng)前薪水情況，給出dept_no, emp_no以及salary，當(dāng)前表示to_date='9999-01-01'
CREATE TABLE dept_manager (
dept_no char(4) NOT NULL,
emp_no int(11) NOT NULL,
from_date date NOT NULL,
to_date date NOT NULL,
PRIMARY KEY (emp_no,dept_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));

select t1.dept_no, t1.emp_no, t2.salary 
from dept_manager as t1 
inner join salaries as t2 
on t1.emp_no = t2.emp_no
and t1.to_date = '9999-01-01'
and t2.to_date = '9999-01-01';

10.獲取所有非manager的員工emp_no
CREATE TABLE dept_manager (
dept_no char(4) NOT NULL,
emp_no int(11) NOT NULL,
from_date date NOT NULL,
to_date date NOT NULL,
PRIMARY KEY (emp_no,dept_no));
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));

select emp_no
from employees
where emp_no not in 
(select emp_no from dept_manager);