题目：

#1.查询和Zlotkey相同部门的员工姓名和工资#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。#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#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#5.查询在部门的location_id为1700的部门工作的员工的员工号#6.查询管理者是King的员工姓名和工资#7.查询工资最低的员工信息: last_name, salary#8.查询平均工资最低的部门信息#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）#10.查询平均工资最高的 job 信息#11.查询平均工资高于公司平均工资的部门有哪些?#12.查询出公司中所有 manager 的详细信息#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?#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#15. 查询部门的部门号，其中不包括job_id是"ST_CLERK"的部门号#16. 选择所有没有管理者的员工的last_name#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'#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）#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）#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）

综合练习

#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_idFROM employeesWHERE 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 salaryFROM employeesWHERE job_id = 'SA_MAN'
);#4*.查询 名字包含'%u%' 的 部门， 打印与其同部门的员工id，名字
SELECT employee_id,last_name
FROM employees 
WHERE department_id = ANY
(SELECT DISTINCT department_idFROM 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_idFROM departmentsWHERE location_id = 1700
);#6.查询管理者是King的员工姓名和工资
SELECT e.last_name,e.salary,m.last_name
FROM employees e, employees m 
WHERE e.manager_id = m.employee_id
AND m.last_name = 'king';SELECT last_name,salary,last_name
FROM employees
WHERE last_name IN
(SELECT last_nameFROM employeesWHERE 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 <= ALL
(SELECT salaryFROM employees
);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
# 方式一：
SELECT *
FROM departments d1 , (SELECT AVG(salary) avg_sal,department_idFROM employeesGROUP BY department_idORDER BY avg_sal ASCLIMIT 0,1) d2
WHERE d1.department_id = d2.department_id;# 方式二# 方式三# 方式四#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 d1.*,d2.department_id,d2.avg_sal
FROM departments d1 , (SELECT AVG(salary) avg_sal,department_idFROM employeesGROUP BY department_idORDER BY avg_sal ASCLIMIT 0,1) d2
WHERE d1.department_id = d2.department_id;#10.查询平均工资最高的 job 信息
SELECT  j.*,e.avg_sal
FROM jobs j,(SELECT AVG(salary) avg_sal,job_idFROM employeesGROUP BY job_idORDER BY avg_sal DESCLIMIT 0,1) e
WHERE j.job_id = e.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
SELECT DISTINCT m.*
FROM employees e,employees m
WHERE e.manager_id = m.employee_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?
SELECT e1.department_id,e2.max_sal
FROM employees e1 , (SELECT MAX(salary) max_sal,department_idFROM employees e2 GROUP BY department_idORDER BY max_sal LIMIT 0,1
)e2
WHERE e1.department_id = e2.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
SELECT employee_id, last_name,m.department_id,email,salary
FROM employees e , (SELECT AVG(salary) avg_sal,department_idFROM employees m GROUP BY department_id,employee_idORDER BY avg_sal DESCLIMIT 0,1
) m
WHERE e.department_id = m.department_id
LIMIT 0,1;#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 departments
WHERE department_id NOT IN 
(SELECT DISTINCT department_idFROM employeesWHERE 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 e1
WHERE NOT EXISTS 
(SELECT *FROM employees e2 WHERE e1.manager_id = e2.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'
SELECT e.employee_id,e.last_name,e.hire_date,e.salary
FROM employees e JOIN employees m 
WHERE e.manager_id = m.employee_id
AND m.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
FROM employees e1
WHERE salary > 
(SELECT AVG(salary)FROM employees e2WHERE e1.department_id = e2.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,department_id
FROM departments d
WHERE 5 < 
(SELECT COUNT(*)FROM employees eWHERE d.department_id = e.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
);