1.显示所有员工的姓名，部门号和部门名称。

  1. select last_name,d.department_id,department_name from employees e,departments d
  2. 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 job_id,location_id from employees e,departments d
where e.department_id=d.department_id
and e.department_id=90

3. 选择所有有奖金的员工的

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

4.选择city在Toronto工作的员工的

select last_name,job_id,d.department_id,department_name
from employees e,departments d,locations l
where e.department_id=d.department_id
and d.location_id=l.location_id
and city='Toronto'

5.查询每个工种、每个部门的部门名、工种名和最低工资

select department_name,job_title,min(salary)最低工资
from employees e,departments d,jobs j
where e.department_id=d.department_id
and e.job_id=j.job_id
group by department_name,job_title;

6.查询每个国家下的部门个数大于2的国家编号

select country_id,count(*)部门个数 from departments d,locations l
where d.location_id=l.location_id
group by country_id
having 部门个数>2;

7、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

employees Emp# manager Mgr#
kochhar 101 king 100

select e.last_name employees,e.employee_id "Emp#",m.last_name manager,m.employee_id "Mgr#"
from employees e,employees m
where e.manager_id=m.employee_id
and e.last_name='kochhar