mysql多表联合查询

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,resultfrom a inner join bon a.id = b.id;

LEFT JOIN 求两个表的交集外加左表剩下的数据

select a.id,name,age,resultfrom a left join bon a.id = b.id;

RIGHT JOIN 两个表的交集外加右表剩下的数据

select a.id,name,age,resultfrom a right join bon a.id = b.id;