1.显示所有员工的姓名，部门号和部门名称

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

2.查询90号部门员工的job_id和90号部门的location_id

DESC locations; #查看表的组成

DESC departments;

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_pct IS NOT NULL;


SELECT * FROM employees WHERE commission_pct IS 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 ,d.department_id,d.department_name
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;

sql92语法

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

DESC departments  #查询表的结构
DESC employees
DESC locations

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，结果类似下面的格式

employees	Emp#	manager	Mgr#
kochhar		101	king	100

SELECT e.last_name "enployees",e.employee_id "Emp#" ,mgr.last_name "manager" ,mgr.employee_id "Mgr#"
FROM employees e LEFT JOIN employees mgr
ON e.manager_id =mgr.employee_id;

7查询那些部门没有员工

SELECT d.department_id
FROM departments d LEFT JOIN employees e
ON d.department_id = e.department_id
WHERE e.department_id IS NULL;

8 查询那个城市没有部门

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;


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_name IN (sales,IT);