SQL Server中多对多关系的实现

多对多的关系必须另外添加一张表来表示

--班级create table banji(banji_id int constraint PK_banji primary key,  --主键banji_num int not null,banji_name nvarchar(20) )--教师create table jiaoshi(jiaoshi_id int constraint PK_jaioshi primary key,  --主键jiaoshi_name nvarchar(20) not null)--班级和教师的关系create table banji_jiaoshi_mapping(banji_id int constraint FK_bnaji_id foreign key references banji(banji_id),    --外键jiaoshi_id int constraint FK_jaoshi_id foreign key references jiaoshi(jiaoshi_id),   --外键kecheng nvarchar(20),constraint PK_banji_id_jiaoshi_id primary key (banji_id, jiaoshi_id, kecheng)    --benji_id, jiaoshi_id, kecheng的三者组合作为主键)

数据库关系图：