How can I use join w/o using the tables primary key when mapping an object?

<join> seems to only allow using the primary key.
<many-to-one> tag seems to require that the property being set is another <class> defined in the xml file

ex:

Java Object:
public class ServiceUser
{
...
private Integer idIndex;
private String loginId;
private String serviceCd;
private String serviceDesc;
...
}

service_user table - table of users and service subscriptions. a login id can subscribe to only one service
id_index INTEGER
c_loginid CHAR(15)
c_servicecd CHAR(3)


service_codes table - master table of available service codes and descriptions (should be read only)
c_servicecd CHAR(3)
c_servicedesc VARCHAR(50)


sample hibernate.cfg.xml
<class name="ServiceUser" table="service_user">
<id name="idIndex" column="id_index" >
<generator class="increment" />
</id>
<property name="loginId" column="c_loginid" />
<property name="serviceCd" column="c_servicecd" />
<join table="service_codes">
<key column="c_servicecd" update="false" />
<property name="serviceDesc" column="c_servicecd" insert="false" update="false"/>
</join>
</class>

when selecting, hibernate tries to join service_user.id_index with service_codes.c_servicecd


replacing the <join> with
<property name="serviceDesc" formula="SELECT sc.c_servicedesc FROM service_codes sc WHERE sc.c_servicecd= serviceCd"/>

doesnt seem to work either, it gives this error: ILLEGAL SYMBOL ".". SOME SYMBOLS THAT MIGHT BE LEGAL ARE: , FROM INTO

Hibernate 3.0
DB2 db

it seems that you should put your

into braces and add join inside: