7.5.2. 一对一（one to one）

基于连接表的双向一对一关联极为罕见，但也是可行的。

  1. <class name="Person">
  2.     <id name="id" column="personId">
  3.         <generator class="native"/>
  4.     </id>
  5.     <join table="PersonAddress" 
  6.         optional="true">
  7.         <key column="personId" 
  8.             unique="true"/>
  9.         <many-to-one name="address"
  10.             column="addressId" 
  11.             not-null="true"
  12.             unique="true"/>
  13.     </join>
  14. </class>
  16. <class name="Address">
  17.     <id name="id" column="addressId">
  18.         <generator class="native"/>
  19.     </id>
  20.     <join table="PersonAddress" 
  21.         optional="true"
  22.         inverse="true">
  23.         <key column="addressId" 
  24.             unique="true"/>
  25.         <many-to-one name="person"
  26.             column="personId" 
  27.             not-null="true"
  28.             unique="true"/>
  29.     </join>
  30. </class>
  1. create table Person ( personId bigint not null primary key )
  2. create table PersonAddress ( personId bigint not null primary key, addressId bigint not null unique )
  3. create table Address ( addressId bigint not null primary key )