MySQL——多表查询

#user_info表
create table user(
      id int(2) primary key,
      user_name varchar(12) unique,
      password varchar(15) not null,
      real_name varchar(8) not null,
      age int(3)
); 

#address表
create table address(
      id int(2) primary key,
      user_id int(2) not null,
      real_name varchar(8),
      mobile char(11),
      address varchar(150)
); 

insert into user values(1,'浅唱灬幸福','8912@321','王晓明',12);
insert into address values(1,1,'王小明','15516472282','山西太原');
insert into address values(2,1,'王鑫','18404905139','山西大同');
insert into address values(3,1,'任建','15333021730','山西晋城');
 
insert into user values(2,'ぅ浮生若梦〤','56701wz','王楠',36);
insert into address values(4,2,'王楠','15010303314','北京海淀');
insert into address values(5,2,'赵婕','18435224278','山西长治');
 
insert into user values(3,'街角の风铃','27w4921','李晓飞',9);

insert into address values(6,6,'刘倩','13159775555','吉林长春');

1、内连接：取多表之间交集

select ui.*,addr.*  from user_info ui,address addr where ui.id=addr.user_id;

2、外连接
（1）left:查询出该关键字左边表的所有数据

select ui.*,addr.* 
from user_info ui 
left join address addr on ui.id=addr.user_id;

（2）right:查询出该关键字右边表的所有数据

select ui.*,addr.* 
from user_info ui 
right join address addr on ui.id=addr.user_id;

3、多表查询：多表之间必须有关系