Mysql语句中的迷失点

 

CREATE TABLE t1(
 id INT NOT NULL,
 name VARCHAR(20),
 score DOUBLE	
)


INSERT INTO t1(id,name,score) VALUES(1,'A',79)
INSERT INTO t1(id,name,score) VALUES(2,'B',49);
INSERT INTO t1(id,name,score) VALUES(3,'C',59);
INSERT INTO t1(id,name,score) VALUES(4,'D',69);
INSERT INTO t1(id,name,score) VALUES(5,'E',89);
INSERT INTO t1(id,name,score) VALUES(6,'F',19);
INSERT INTO t1(id,name,score) VALUES(7,'G',29);
INSERT INTO t1(id,name,score) VALUES(8,'H',87);
INSERT INTO t1(id,name,score) VALUES(9,'I',86);
INSERT INTO t1(id,name,score) VALUES(10,'J',81);





CREATE TABLE t2(
 id INT NOT NULL,
 sex VARCHAR(20),
 work VARCHAR(20)	
)


INSERT INTO t2(id,sex,work) VALUES(1,'男','策划')
INSERT INTO t2(id,sex,work) VALUES(1,'男','行政');
INSERT INTO t2(id,sex,work) VALUES(1,'男','程序员');
INSERT INTO t2(id,sex,work) VALUES(4,'女','财务');
INSERT INTO t2(id,sex,work) VALUES(5,'女','法务');
INSERT INTO t2(id,sex,work) VALUES(5,'女','运营');
INSERT INTO t2(id,sex,work) VALUES(5,'女','风投');
INSERT INTO t2(id,sex,work) VALUES(7,'男','算法');
INSERT INTO t2(id,sex,work) VALUES(8,'男','分析');
INSERT INTO t2(id,sex,work) VALUES(15,'女','风投1');
INSERT INTO t2(id,sex,work) VALUES(17,'男','算法2');
INSERT INTO t2(id,sex,work) VALUES(18,'男','分析3');



SELECT * FROM t1 RIGHT JOIN t2 ON t1.id = t2.id

SELECT * FROM t1 LEFT JOIN t2 ON t1.id = t2.id

SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id

1.关于内左右连接的区分

 

1.内连接  inner join

2.左连接 left join

3.右连接 right join

有点区别