[打卡]张博研—多表查询

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

SELECT employee_id,department_name
from employees e FULL OUTER JOIN departments d
ON e.department_id=d.department_id;

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

SELECT employee_id,department_name
from employees e LEFT 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 employee_id,department_name
from employees e LEFT JOIN departments d
ON e.department_id=d.department_id
WHERE d.department_id is null;

SELECT employee_id,department_name
from employees e RIGHT JOIN departments d
ON e.department_id=d.department_id
WHERE e.department_id is null;

SELECT employee_id,department_name
from employees e LEFT JOIN departments d
ON e.department_id=d.department_id
UNION ALL
SELECT employee_id,department_name
from employees e RIGHT JOIN departments d
ON e.department_id=d.department_id
WHERE e.department_id is null;

SELECT employee_id,department_name
from employees e RIGHT JOIN departments d
ON e.department_id=d.department_id
UNION ALL
SELECT employee_id,department_name
from employees e LEFT JOIN departments d
ON e.department_id=d.department_id
WHERE d.department_id is null;

SELECT employee_id,department_name
from employees e LEFT JOIN departments d
ON e.department_id=d.department_id
WHERE d.department_id is null
UNION ALL
SELECT employee_id,department_name
from employees e RIGHT JOIN departments d
ON e.department_id=d.department_id
WHERE e.department_id is null;