P48 第09章_子查询练习题

时间：2025-02-23 08:33:44

第09章_子查询练习题

#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 IN(
		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> ALL(
		SELECT 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,manager_id
FROM employees
WHERE manager_id IN(
			SELECT employee_id
			FROM employees 
			WHERE last_name='King'
			);

#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 *
FROM departments
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)=(
		SELECT MIN(avg_sal)
		FROM(
			SELECT AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			) t_dept_avg_sal
		)
	);

#方式2：

SELECT *
FROM departments
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)<= ALL(
			SELECT AVG(salary) 
			FROM employees
			GROUP BY department_id
			) 
		
	);

#方式3：LIMIT

SELECT *
FROM departments
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)= (
			SELECT AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			ORDER BY avg_sal ASC
			LIMIT 0,1
		)
	);

#方式4：
SELECT d.*
FROM departments d,(
			SELECT department_id,AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			ORDER BY avg_sal ASC
			LIMIT 0,1) t_dept_avg_sal
WHERE d.`department_id`=t_dept_avg_sal.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）

#方式1：
SELECT d.*,(SELECT AVG(salary) 
	FROM employees WHERE department_id=d.`department_id`) avg_sal
FROM departments d
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)=(
		SELECT MIN(avg_sal)
		FROM(
			SELECT AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			) t_dept_avg_sal
		)
	);

#方式2：

SELECT d.*,(SELECT AVG(salary) 
	FROM employees WHERE department_id=d.`department_id`) avg_sal
FROM departments d
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)<= ALL(
			SELECT AVG(salary) 
			FROM employees
			GROUP BY department_id
			) 
		
	);

#方式3：LIMIT

SELECT d.*,(SELECT AVG(salary) 
	FROM employees WHERE department_id=d.`department_id`) avg_sal
FROM departments d
WHERE department_id=(
	SELECT department_id
	FROM employees
	GROUP BY department_id
	HAVING AVG(salary)= (
			SELECT AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			ORDER BY avg_sal ASC
			LIMIT 0,1
		)
	);

#方式4：
SELECT d.*,(SELECT AVG(salary) 
	FROM employees WHERE department_id=d.`department_id`) avg_sal
FROM departments d,(
			SELECT department_id,AVG(salary) avg_sal
			FROM employees
			GROUP BY department_id
			ORDER BY avg_sal ASC
			LIMIT 0,1) t_dept_avg_sal
WHERE d.`department_id`=t_dept_avg_sal.department_id


#10.查询平均工资最高的 job 信息

#方式1：

SELECT *
FROM jobs
WHERE job_id=(
		SELECT job_id
		FROM employees
		GROUP BY job_id
		HAVING AVG(salary)=(
				SELECT MAX(avg_sal)
				FROM(
					SELECT AVG(salary) avg_sal
					FROM employees
					GROUP BY job_id
					) t_job_avg_sal
			)
);

#方式2：

SELECT *
FROM jobs
WHERE job_id=(
		SELECT job_id
		FROM employees
		GROUP BY job_id
		HAVING AVG(salary)>=ALL(
				SELECT AVG(salary) 
				FROM employees
				GROUP BY job_id	
			)
);

#方式3：

SELECT *
FROM jobs
WHERE job_id=(
		SELECT job_id
		FROM employees
		GROUP BY job_id
		HAVING AVG(salary)=(
				SELECT AVG(salary) avg_sal
				FROM employees
				GROUP BY job_id	
				ORDER BY avg_sal DESC
				LIMIT 0,1
			)
);

#方式4：
SELECT j.*
FROM jobs j,(
		SELECT job_id,AVG(salary) avg_sal
		FROM employees
		GROUP BY job_id	
		ORDER BY avg_sal DESC
		LIMIT 0,1) t_job_avg_sal
WHERE j.job_id=t_job_avg_sal.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
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
#方式1：自连接
SELECT DISTINCT mgr.employee_id,mgr.last_name,mgr.job_id,mgr.department_id
FROM employees e1 JOIN employees mgr
ON e1.manager_id=mgr.employee_id

#方式2：子查询

SELECT employee_id,last_name,job_id,department_id
FROM employees
WHERE employee_id IN(
		SELECT DISTINCT manager_id
		FROM employees
		);

#方式3：使用exists
SELECT employee_id,last_name,job_id,department_id
FROM employees e1
WHERE EXISTS(
		SELECT *
		FROM employees e2
		WHERE e1.`employee_id`=e2.`manager_id`
		);


#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?

#方式1：
SELECT MIN(salary)
FROM employees
WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING MAX(salary)=(
						SELECT MIN(max_sal)
						FROM(
							SELECT MAX(salary) max_sal
							FROM employees
							GROUP BY department_id
							) t_dept_max_sal
			)
);

#方式2：

SELECT MIN(salary)
FROM employees
WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING MAX(salary)<= ALL(
						
						SELECT MAX(salary)
						FROM employees
						GROUP BY department_id
							
			)
);

#方式3：

SELECT MIN(salary)
FROM employees
WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING MAX(salary)=(
						
						SELECT MAX(salary) max_sal
						FROM employees
						GROUP BY department_id
						ORDER BY max_sal ASC
						LIMIT 0,1	
			)
);

#方式4：
SELECT MIN(salary)
FROM employees e,(

			SELECT department_id,MAX(salary) max_sal
			FROM employees
			GROUP BY department_id
			ORDER BY max_sal ASC
			LIMIT 0,1
) t_dept_max_sal
WHERE e.department_id=t_dept_max_sal.department_id

#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

#方式1：
SELECT last_name,department_id,email,salary
FROM employees
WHERE employee_id =ANY(
	SELECT DISTINCT manager_id
	FROM employees
	WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING AVG(salary)=(
						SELECT MAX(avg_sal)
						FROM(
							SELECT AVG(salary) avg_sal
							FROM employees
							GROUP BY department_id
							) t_dept_avg_sal
				)
	)
);

#方式2：

SELECT last_name,department_id,email,salary
FROM employees
WHERE employee_id =ANY(
	SELECT DISTINCT manager_id
	FROM employees
	WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING AVG(salary)>=ALL(
				
						SELECT AVG(salary) avg_sal
						FROM employees
						GROUP BY department_id
						ORDER BY avg_sal DESC
					
				)
	)
);

#方式3:

SELECT last_name,department_id,email,salary
FROM employees
WHERE employee_id =ANY(
	SELECT DISTINCT manager_id
	FROM employees
	WHERE department_id=(
			SELECT department_id
			FROM employees
			GROUP BY department_id
			HAVING AVG(salary)=(
				
						SELECT AVG(salary) avg_sal
						FROM employees
						GROUP BY department_id
						ORDER BY avg_sal DESC
					        LIMIT 0,1
				)
	)
);

#方式4：

SELECT last_name,department_id,email,salary
FROM employees
WHERE employee_id IN(
			SELECT DISTINCT manager_id
			FROM employees e,(
					SELECT department_id,AVG(salary) avg_sal
					FROM employees
					GROUP BY department_id
					ORDER BY avg_sal DESC
					LIMIT 0,1
					) t_dept_avg_sal
			WHERE e.`department_id`=t_dept_avg_sal.department_id
			);


#15. 查询部门的部门号，其中不包括job_id是"ST_CLERK"的部门号

#方式1：
SELECT department_id
FROM departments
WHERE department_id NOT IN(
			SELECT DISTINCT department_id
			FROM employees
			WHERE job_id='ST_CLERK'
			);

#方式2：
SELECT department_id
FROM departments d
WHERE NOT EXISTS(
			SELECT *
			FROM employees e
			WHERE d.`department_id`=e.`department_id`
			AND e.`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 emp
WHERE NOT EXISTS(
		SELECT *
		FROM employees mgr
		WHERE emp.`manager_id`=mgr.`employee_id`
		)


#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'
# 方式1：
SELECT employee_id,last_name,hire_date,salary
FROM employees
WHERE manager_id=(
			SELECT employee_id
			FROM employees
			WHERE last_name='De Haan'
			);
#方式2：
SELECT employee_id,last_name,hire_date,salary
FROM employees e1
WHERE EXISTS(
		SELECT *
		FROM employees e2
		WHERE e1.`manager_id`=e2.`employee_id`
		AND e2.`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 last_name,salary,department_id
FROM employees e1
WHERE salary>(
		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 d
WHERE 5< (
		SELECT COUNT(*)
		FROM employees e
		WHERE e.`department_id`=d.`department_id`
		)

#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 l
WHERE 2<(
	SELECT COUNT(*)
	FROM departments d
	WHERE l.location_id=d.`location_id`
	);

SELECT *
FROM locations
SELECT *FROM departments

/*
子查询的编写技巧(或步骤):① 从里往外写 ②从外往里写

如何选择？
①如果子查询相对较简单，从外往里写，若子查询结构复杂，则从里往外写
②如果是相关子查询的话，通常都是从外往里写

*/

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