排序与分页，多表查询课后练习

#第五章排序与分页的课后练习

#第五章排序与分页课后练习

#1.查询员工的姓名和部门号和年薪，按年薪降序，按姓名升序显示
SELECT salary*12 AS’年薪’,last_name,department_id
FROM employees
ORDER BY '年薪’DESC,last_name ASC;

#2.选择工资不在8000到17000的员工姓名和工资，按工资降序，显示第21到40位置的数据
SELECT last_name,salary
FROM employees
WHERE salary NOT BETWEEN 8000 AND 17000
ORDER BY salary DESC
LIMIT 20,20

#3.查询邮箱中包含e的员工信息，并且先按邮箱的字节数降序，再按部门号升序
SELECT employee_id,last_name,email,department_id
FROM employees
#where email like’%e%’
WHERE email REGEXP’[e]’
ORDER BY LENGTH(email) DESC,department_id ASC;

第六章多表查询课后练习
【题目】

1.显示所有员工的姓名，部门号和部门名称。 有所有的字眼出现，是外连接问题

SELECT e.last_name,e.department_id,d.department_name
FROM employees e LEFT JOIN departments d
ON e.department_id=d.department_id;

2.查询90号部门员工的job_id和90号部门的location_id

SELECT e.job_id,d.location_id
FROM employees e JOIN departments d
ON e.department_id=d.department_id
WHERE d.department_id=90;

3.选择所有有奖金的员工的 last_name , department_name , location_id , city

SELECT e.last_name , e.commission_pct,d.department_name , d.location_id , l.city
FROM employees e LEFT JOIN departments d
ON e.department_id=d.department_id
LEFT JOIN locations l
ON d.location_id=l.location_id
WHERE e.commission_pctIS NOT NULL;

4.选择city在Toronto工作的员工的 last_name , job_id , department_id , department_name

SELECT e.last_name , e.job_id , e.department_id , d.department_name,l.city
FROM employees e
JOIN departments d
ON e.department_id=d.department_id
JOIN locations l
ON d.location_id=l.location_id
WHERE l.city=‘Toronto’;

5.查询员工所在的部门名称、部门地址、姓名、工作、工资，其中员工所在部门的部门名称为’Executive’

SELECT d.department_name,l.street_address,e.last_name,e.job_id,e.salary
FROM employees e
JOIN departments d
ON e.department_id=d.department_id
JOIN locations l
ON d.location_id=l.location_id
WHERE d.department_name=‘Executive’;

#有的部门没有员工但应该显示其结构，可能有的部门在不同城市都有location_id，考虑全面的话，把join改成left join

6.选择指定员工的姓名，员工号，以及他的管理者的姓名和员工号

#结果类似于下面的格式, 其实就是起别名的方式来输出,再加上表的自连接，领导id与员工id
employees Emp# manager Mgr#
kochhar 101 king 100

SELECT emp.last_name’employees’,emp.employee_id’Emp#‘,mgr.last_name’manager’,mgr.employee_id’Mgr#’
FROM employees emp JOIN employees mgr
ON emp.manager_id=mgr.employee_id;

7.查询哪些部门没有员工

SELECT d.department_id
FROM departments d LEFT JOIN employees e
ON d.department_id=e.department_id
WHERE e.department_idIS NULL;
#本题目也可以用子查询来实现
SELECT department_id
FROM departments d
WHERE NOT EXISTS (
SELECT *
FROM employees e
WHERE e.department_id = d.department_id
)

8. 查询哪个城市没有部门

SELECT l.location_id,l.city
FROM locations l LEFT JOIN departments d
ON l.location_id=d.location_id
WHERE d.location_id IS NULL;
#如果不放心上面语句查询的可以做一下检查
SELECT department_id
FROM departments
WHERE department_id IN(1000,1100,1200,1300,1600);

9. 查询部门名为 Sales 或 IT 的员工信息

SELECT e.employee_id,e.last_name,e.department_id
FROM employees e JOIN departments d
ON e.department_id=d.department_id
WHERE d.department_nameIN (‘Sales’,‘IT’);