Nosuchpgmr's Blog

自然連接

SELECT employee_id, department_name
FROM employee e JOIN department d
ON e.department_id = d.department_id
AND e.manager_id = d.manager_id;

等同于

SELECT employee_id, department_name
FROM employee e NATURAL JOIN department d;

自動查詢兩張表中所有相同的字段，然后進行等值連接

USING

SELECT employee_id, department_name
FROM employee e JOIN department d
ON e.department_id = d.department_id;

等同于

SELECT employee_id, department_name
FROM employee e JOIN department d
USING (department_id);