create database one20210605 default charset=utf8;
use one20210605;
create table student(
sid int ,
`sname`varchar(10),
saddrress varchar (100)
);
create table course (
cid int , # 课程id
sid int , #
cname varchar(100)
);
insert into student values (1 , '关羽',"许昌"),(2 , '诸葛亮',"南阳"),(3 , '张飞',"河北"),(4 , '刘备',"四川")
(5 ,"阿斗","蜀国");
insert into course values (101 ,1 "三百回合不累法"),(102 , 2,"劝人投降话术"),(101 , 3,"三百回合不累法"),(102 , 4 ,"劝人投降话术"),(103 ,1 "如何俘获大乔和小乔");
select * from student;
select * from course;
-- 交叉查询 (迪卡尔积查询)
select * from student , course;
select * from student , course where student.sid= course.sid;
-- 内连接
select * from student inner join course on student.sid=course.sid;
--左外链接
select * from student left join course on student.sid=course.sid;
--右外连接
select * from student right course on student.sid=course.sid;
-- 全外连接
select * from student full course on student.sid=course.sid;