数据获取

表的数据信息(sql文件)放在这个链接里了，提取码：52xz，需要的自行提取。数据来自网上的练习，已经给小伙伴们总结好了。

将数据导入到mysql中

大家可以直接在navicat运行该脚本，就可以直接导入数据了，如果遇到问题很可能是编码问题，改一下数据库的编码为gb2312，如图：

基础20题

点击新建查询就可以写我们的mysql基础20题了。

#(1)查询和Zlotkey相同部门的员工姓名和工资
SELECT
	last_name,
	salary 
FROM
	employees 
WHERE
	department_id = ( SELECT department_id from employees WHERE last_name = "Zlotkey" );
#(2)查询工资比公司平均工资高的员工的员工号，姓名和工资。
SELECT
	employee_id,
	last_name,
	salary
FROM
	employees
WHERE
	salary > (SELECT AVG(salary) FROM employees);
#(3)选择工资大于所有JOB_ID = SA_MAN 的员工的工资的员工的last_name, job_id, salary
SELECT
	last_name,
	job_id,
	salary 
FROM
	employees 
WHERE
	salary > ( SELECT max( salary ) FROM employees WHERE job_id = "SA_MAN" );
#(4)查询和姓名中包含字母u的员工在相同部门的员工的员工号和姓名
SELECT
	employee_id,
	last_name 
FROM
	employees 
WHERE
	department_id IN (
	SELECT DISTINCT
	( department_id ) 
	FROM
	employees 
	WHERE
	last_name LIKE "%u%")
	
#(5)查询在部门的location_id为1700的部门工作的员工的员工号
SELECT
	employee_id 
FROM
	employees 
WHERE
	department_id IN ( SELECT department_id FROM departments WHERE location_id = 1700 );
	
#(6)查询管理者是King的员工姓名和工资
SELECT
	last_name,
	salary 
FROM
	employees 
WHERE
	manager_id IN ( SELECT employee_id FROM employees WHERE last_name = "K_ing" );
#(7)查询工资最低的员工信息: last_name, salary
SELECT
	last_name,
	salary 
FROM
	employees 
WHERE
	salary = ( SELECT min( salary ) FROM employees );
	
#(8)查询平均工资最低的部门信息
SELECT
	 b.department_id,
	 d.department_name,
	 d.manager_id,
	 d.location_id
FROM
	departments d
	JOIN (
	SELECT
	department_id,
	AVG( salary ) AS avg_salary 
	FROM
	employees 
	GROUP BY
	department_id 
	HAVING
	avg_salary IN ( 
	SELECT 
	MIN( a.avg_salary ) 
	FROM ( 
	SELECT 
	department_id, 
	AVG( salary ) AS avg_salary 
	FROM employees 
	GROUP BY department_id 
	) AS a 
	) 
 ) AS b 
	ON d.department_id = b.department_id;
#(9)查询平均工资最低的部门信息和该部门的平均工资（相关子查询）
SELECT
	 b.department_id,
	 d.department_name,
	 d.manager_id,
	 d.location_id,
	 b.avg_salary
FROM
	departments d
	JOIN (
	SELECT
	department_id,
	AVG( salary ) AS avg_salary 
	FROM
	employees 
	GROUP BY
	department_id 
	HAVING
	avg_salary IN ( 
	SELECT 
	MIN( a.avg_salary ) 
	FROM ( 
	SELECT 
	department_id, 
	AVG( salary ) AS avg_salary 
	FROM employees 
	GROUP BY department_id 
	) AS a 
	)
 ) AS b 
	ON d.department_id = b.department_id;
#(10)查询平均工资最高的 job 信息
SELECT
	b.job_id,
	j.job_title,
	j.min_salary,
	j.max_salary
FROM
	jobs j 
JOIN
	(
	SELECT
	job_id ,
	AVG(salary) AS avg_salary 
	FROM
	employees
	GROUP BY
	job_id
	HAVING
	avg_salary in 
	(
	SELECT
	MAX(a.avg_salary)
	FROM
	(
	SELECT
	job_id,
	AVG( salary ) AS avg_salary 
	FROM
	employees 
	GROUP BY
	job_id
	) as a 
	)
)as b 
ON j.job_id = b.job_id;
#(11)查询平均工资高于公司平均工资的部门有哪些?
SELECT
	department_id,
	AVG(salary) as avg_salary
FROM
	employees
WHERE
	department_id is not null 
GROUP BY
	department_id
HAVING
	avg_salary > (
	SELECT 
	AVG(salary) 
	FROM 
	employees );
#(12)查询出公司中所有 manager 的详细信息
SELECT
	*
FROM
	employees
WHERE
	employee_id in
	(
	SELECT 
	DISTINCT manager_id 
	FROM 
	employees);
#(13)各个部门中 最高工资中最低的那个部门的 最低工资是多少?
SELECT 
	MAX(salary) as max_salary 
FROM 
	employees 
WHERE 
	department_id is not null 
GROUP BY 
	department_id 
ORDER BY 
	max_salary 
LIMIT 0,1;
#(14)查询平均工资最高的部门的 manager 的详细信息: last_name, department_id, email, salary
SELECT
	last_name,
	department_id,
	email,
	salary
FROM
 employees
WHERE 
	employee_id in
	(
	SELECT
	 DISTINCT manager_id
	FROM
	employees
	WHERE
	department_id = (
	SELECT
	department_id
	FROM
	employees 
	GROUP BY
	department_id 
	HAVING
	AVG( salary ) IN ( 
	 SELECT 
	MAX( a.avg_salary ) 
	FROM 
	( 
	SELECT 
	department_id, 
	AVG( salary ) AS avg_salary 
	FROM 
	employees 
	GROUP BY 
	department_id 
	) AS a 
	) 
	)
	);
#(15)查询部门的部门号，其中不包括job_id是"ST_CLERK"的部门号
SELECT
	department_id
FROM
	employees
WHERE
	job_id NOT IN (
	SELECT 
	job_id 
	FROM 
	employees 
	WHERE 
	job_id = "ST_CLERK");
#(16)选择所有没有管理者的员工的last_name
SELECT 
	last_name 
FROM 
	employees 
WHERE 
	manager_id is null;
#(17)查询员工号、姓名、雇用时间、工资，其中员工的管理者为 ‘De Haan’
SELECT
	employee_id,
	last_name,
	hiredate,
	salary
FROM
	employees
WHERE
	manager_id = (SELECT
	employee_id
FROM
	employees
WHERE
	last_name = "De Haan");
#(18)查询各部门中工资比本部门平均工资高的员工的员工号, 姓名和工资（相关子查询）
SELECT employee_id,last_name,salary,department_id
FROM employees e1
WHERE salary > (
	# 查询某员工所在部门的平均
	SELECT AVG(salary)
	FROM employees e2
	WHERE e2.department_id = e1.`department_id`);
#(19)查询每个部门下的部门人数大于 5 的部门名称（相关子查询）
SELECT
	department_name
FROM
	departments 
WHERE	
	department_id in (
	SELECT
	department_id
	FROM
	employees
	GROUP BY
	department_id
	HAVING
	COUNT(*) > 5);
#(20)查询每个国家下的部门个数大于 2 的国家编号（相关子查询）
SELECT
	country_id
FROM
	locations
WHERE
	location_id in ( 
	SELECT
	location_id
	FROM
	departments
	GROUP BY
	location_id
	HAVING
	COUNT(*) > 2);
好了，今天的分享已经结束了，以后我还会多多更新这些对于大数据技术较为基础的相关分享，希望大家能共同进步，一起加油！