欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

mysql多表联合查询

程序员文章站 2022-03-31 22:00:02
创建表a插入数据create table a( `id` int(11) primary key , `name` varchar(6) not null , `age` int(4) not null);insert into a values (1,'111',20);insert into a values (2,'222',20);insert into a values (3,'333',20);insert into a values (4,'444',2....

创建表a插入数据

create table a(
    `id` int(11) primary key ,
    `name` varchar(6) not null ,
    `age` int(4) not null
);
insert into a values (1,'111',20);
insert into a values (2,'222',20);
insert into a values (3,'333',20);
insert into a values (4,'444',20);

创建表b插入数据

create table  b(
    `id` int(11) primary key ,
    `result` float
);
insert into b values (1,11);
insert into b values (2,22);
insert into b values (5,11);

.内连接:INNER JOIN 求两个表的交集

select a.id,name,age,result
from a inner join b
on a.id = b.id;
id name age result
1 1 111 20 11
2 2 222 20 22

LEFT JOIN 求两个表的交集外加左表剩下的数据

select a.id,name,age,result
from a left join b
on a.id = b.id;
id name age result
1 1 111 20 11
2 2 222 20 22
3 3 333 null null
4 4 444 null null

RIGHT JOIN 两个表的交集外加右表剩下的数据

select a.id,name,age,result
from a right join b
on a.id = b.id;
id name age result
1 1 111 20 11
2 2 222 20 22
3 null null null 11

本文地址:https://blog.csdn.net/qq_43839730/article/details/107640265

相关标签: mysql