1.自然连接
NATURAL JOIN : 它会帮你自动查询两张连接表中所有相同的字段
,然后进行等值连接
。
不够灵活。
SELECT employee_id,last_name,department_name
FROM employees e JOIN departments d
ON e.`department_id` = d.`department_id`
AND e.`manager_id` = d.`manager_id`;
#使用NATURAL
SELECT employee_id,last_name,department_name
FROM employees e NATURAL JOIN departments d;
2.USING
指定数据表里的同名字段
进行等值连接,不能在自连接中使用
SELECT employee_id,last_name,department_name
FROM employees e JOIN departments d
ON e.department_id = d.department_id;
#使用USING
SELECT employee_id,last_name,department_name
FROM employees e JOIN departments d
USING (department_id);
标签:JOIN,name,连接,SQL99,MySQL,department,USING,id
From: https://www.cnblogs.com/zhishu/p/16596445.html