多表查询练习

1. 显示所有员工的姓名，部门号和部门名称。

select e.last_name,d.department_id,d.department_id from employees e,departments d where 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,departments d where e.department_id=d.department_id and d.department_id=90;

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

select e.last_name,d.department_name,l.location_id,l.city from employees e,departments d,locations l where e.department_id=d.department_id and d.locatiion_id=l.location_id and e.commission_pct is not null;

4. 选择在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,departments d,locations l where e.department_id=d.department_id and d.location_id=l.location_id and l.city='Toronto';

5. 选择所有员工的姓名，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

employees	Emp#	manager	Mgr#
kochhar	101	king	100

select e.last_name "employees",e.employee_id "Emp#",d.last_name "manager",d.manager_id "Mgr#" from employees e,employees d where e.manager_id=d.employee_id(+);

6. 查询各部门员工姓名和他们的同事姓名，结果类似于下面的格式

Department_id	Last_name	colleague
20	fay	hartstein

select e.department_id "Department_id",e.last_name "Last_name",c.last_name "colleague" from employees e join employees c on(e. department_id =c. department_id) where e.employee_id<>c.employee_id;