编辑代码

CREATE DATABASE test;
use test;
CREATE TABLE s1 (
	id int,
	name varchar(255),
	address varchar(255),
	city varchar(255)
);

INSERT INTO s1 VALUES (1, '张1', '李四1', '杭州1');
INSERT INTO s1 VALUES (2, '李1',  '张三1', '北京1');

CREATE TABLE s2 (
	id int,
	name varchar(255),
	address varchar(255),
	city varchar(255)
);

INSERT INTO s2 VALUES (1, '张2', '李四2', '杭州2');
INSERT INTO s2 VALUES (3, '李2',  '张三2', '北京2');

CREATE TABLE s3 (
	id int,
	name varchar(255),
	address varchar(255),
	city varchar(255)
);

INSERT INTO s3 VALUES (1, '张3', '李四3', '杭州3');
INSERT INTO s3 VALUES (2, '李3',  '张三3', '北京3');
INSERT INTO s3 VALUES (4, '李3',  '张三3', '北京3');


SELECT * FROM s1 left outer join s2 on s1.id = s2.id;
SELECT * FROM s1 right outer join s2 on s1.id = s2.id;

SELECT * FROM s1 left outer join s2 using(id);

SELECT s1.* FROM s1 left outer join s2 using(id);

SELECT s2.* FROM s1 left outer join s2 using(id);

SELECT s1.*, s2.* FROM s1 left outer join s2 using(id);

SELECT * FROM s1 right outer join s2 using(id);
SELECT * FROM s1 join s2 using(id);

select * from s1 left join s2 using (id);
select * from s1 left join s2 using (id) right join s3 using (id);