数据库SQL实战练习1

题目描述

1、查找最晚入职员工的所有信息

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 *
FROM employees
ORDER BY hire_date desc limit 1;

2、查找入职员工时间排名倒数第三的员工所有信息（表同上）

SELECT *
FROM employees
ORDER BY hire_date desc limit 2,1;

3、查找各个部门当前(to_date=‘9999-01-01’)领导当前薪水详情以及其对应部门编号dept_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 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 s.* , d.dept_no
from   salaries  s,dept_manager d
where d.to_date = '9999-01-01'
and s.to_date = '9999-01-01'
and d.emp_no = s.emp_no;
/*
SELECT s.*, d.dept_no 
FROM salaries s ,  dept_manager d
WHERE s.to_date='9999-01-01'
AND d.to_date='9999-01-01'
AND s.emp_no = d.emp_no;
*/

4、查找所有已经分配部门的员工的last_name和first_name

CREATE TABLE dept_emp (
emp_no int(11) NOT NULL,
dept_no char(4) 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 last_name , first_name,dept_no
FROM  dept_emp d, employees e
WHERE d.emp_no = e.emp_no

5、查找所有员工的last_name和first_name以及对应部门编号dept_no，也包括展示没有分配具体部门的员工

CREATE TABLE dept_emp (
emp_no int(11) NOT NULL,
dept_no char(4) 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 e.last_name , e.first_name,d.dept_no
FROM employees e  left join  dept_emp d on d.emp_no = e.emp_no;

6、查找所有员工入职时候的薪水情况，给出emp_no以及salary， 并按照emp_no进行逆序

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));

SELECT e.emp_no,s.salary
FROM employees e, salaries s
WHERE e.emp_no = s.emp_no
AND e.hire_date = s.from_date
ORDER BY e.emp_no desc;

7、查找薪水涨幅超过15次的员工号emp_no以及其对应的涨幅次数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));

SELECT emp_no ,count(salary) as t
FROM salaries
GRIUP BY emp_no
HAVING t>15;

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