创建表和演示数据

if not exists(select * from sysobjects where name='stu')

    create table stu

    (

        s_id int identity(1,1),

        s_name varchar(50),

        s_class int

    );

if not exists(select * from sysobjects where name='class')

    create table class

    (

        c_id  int identity(1,1),

        c_name varchar(50)

    );

go

truncate table class

insert into class values('计算机200701班')

insert into class values('计算机200702班')

insert into class values('电子商务200701班')

insert into class values('电子商务200702班')

go

truncate table stu

 

insert into stu values('张三',1)

insert into stu values('李四',2)

insert into stu values('王五',3)

insert into stu values('刘六',5)

 

查询演示

 

 

 

 

 

 

1、左连接(Left Join)

select * from stu left join class on s_class=c_id

 

2、右连接(Right Join)

select * from stu right join class on s_class=c_id

3、内连接(Inner Join)

select * from stu inner join class on s_class=c_id

4、完全连接(Full Join)

select * from stu full join class on s_class=c_id

5、交叉连接(Cross Join)

select * from stu cross join class order by s_name