[打卡]内连接&外连接

SELECT e.employee_id,d.department_name
from employees e,departments d
WHERE e.department_id=d.department_id;
#内连接
SELECT * from employees;

SELECT employee_id,department_name
from employees e JOIN departments d
on e.department_id=d.department_id;

SELECT employee_id,department_name,city
from employees e JOIN departments d
on e.department_id=d.department_id
join locations l
on d.location_id=l.location_id;

SELECT employee_id,department_name
from employees e LEFT OUTER JOIN departments d
on e.department_id=d.department_id;

SELECT employee_id,department_name
from employees e RIGHT JOIN departments d
on e.department_id=d.department_id;

SELECT 122-106;