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！

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