多對多的雙向關聯:(非常少用)
通過老師可以知道他教了多少學生,這是單項多對多。而如果同時通過學生知道有多少個老師教他,那麼就是多對多雙向的關聯。
xml實作:
student.java:
teacher.java:
配置檔案:
student.hbm.xml:
teacher.hbm.xml:
在hibernate.cfg.xml中配置:
生成的sql語句:
create table t_s (
student_id integer not null,
teacher_id integer not null,
primary key (teacher_id, student_id)
)
create table xm_student (
id integer not null auto_increment,
name varchar(255),
primary key (id)
create table xm_teacher (
alter table t_s
add index fk1bf687b5893c2 (teacher_id),
add constraint fk1bf687b5893c2
foreign key (teacher_id)
references xm_teacher (id)
add index fk1bf686abd4922 (student_id),
add constraint fk1bf686abd4922
foreign key (student_id)
references xm_student (id)
轉載請注明出處:http://blog.csdn.net/acmman