7.4.2. One-to-one
A bidirectional one-to-one association on a foreign key is common:
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <many-to-one name="address" column="addressId" unique="true" not-null="true"/> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> <one-to-one name="person" property-ref="address"/> </class>
create table Person ( personId bigint not null primary key, addressId bigint not null unique ) create table Address ( addressId bigint not null primary key )
A bidirectional one-to-one association on a primary key uses the special id generator:
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <one-to-one name="address"/> </class> <class name="Address"> <id name="id" column="personId"> <generator class="foreign"> <param name="property">person</param> </generator> </id> <one-to-one name="person" constrained="true"/> </class>
create table Person ( personId bigint not null primary key ) create table Address ( personId bigint not null primary key )