7.3.2. Many-to-one
A unidirectional many-to-one association on a join table is common when the association is optional. For example:
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <join table="PersonAddress" optional="true"> <key column="personId" unique="true"/> <many-to-one name="address" column="addressId" not-null="true"/> </join> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> </class>
create table Person ( personId bigint not null primary key ) create table PersonAddress ( personId bigint not null primary key, addressId bigint not null ) create table Address ( addressId bigint not null primary key )