mysql right join实例_mysql left join right join inner join简单实例

-- 准备工作

drop table if exists Emp;

create table if not exists Emp

(

uid int primary key,

sid int

);

insert into Emp values(1,1);

insert into Emp values(2,2);

drop table if exists Sal;

create table if not exists Sal

(

sid int primary key,

salary float

);

insert into Sal values(1,11);

insert into Sal values(3,33);

-- 查看结果

select * from Emp left join Sal on Emp.sid = Sal.sid;

左表为主(左表内容至少全部出现一次)

uid

sid

sid

salary

1

1

1

11

2

2

NULL

NULL

select * from Emp right join Sal on Emp.sid = Sal.sid;

右表为主(右表内容至少全部出现一次)

uid

sid

sid

salary

1

1

1

11

NULL

NULL

3

33

select * from Emp inner join Sal on Emp.sid = Sal.sid;

相当于上面两表求交集

uid

sid

sid

salary

1

1

1

11

原文：/playSCforever/p/3970788.html