Hibernate关联关系映射
关联关系映射的分类可以遵行这样一个原则：双向还是单项、是否有链接表， 依赖主键还是外键。?
<generator class="native"/>?
</id>?
</class>?
create table Person ( personId bigint not null primary key )?
create table PersonAddress ( personId not null, addressId bigint not null primary key )?
create table Address ( addressId bigint not null primary key )
