I am new to Hibernate and was wondering what would be the best way to define association between these tables in the hibernate mapping file.

create table meta_data (
metadata_id identity not null primary key,
meta_name varchar(25) not null,
meta_code varchar(10) not null,
description varchar(255) not null,
parent_meta_name varchar(25),
parent_meta_code varchar(10));

The meta_name, meta_code, parent_meta_name, and parent_meta_code uniquely identify a row within meta_data table.

create table incident (
incident_id identity not null primary key,
description varchar(150) not null,
incident_type varchar(1) not null,
incident_cause varchar(2) not null);

The tables do not have a foreign key relationship. Here is the query I would like to implement in HQL.

select i.*, mt.description, mc.description
from incident i, meta_data mt, meta_data mc
where mt.meta_name = 'incident_type'
and mt.meta_code = i.incident_type
and mc.meta_name = 'incident_cause'
and mc.meta_code = i.incident_cause

Beside the 'incident' table, there are several other tables with fields that are associated with the meta_data table. From what I understand, Hibernate supports arbitrary join condition using a formula and property-ref. However, in my case it does not work since parent name and code columns in meta data table can be null.

Redesigning the existing database schema is not an option.