Hibernate：如何为一个表映射两列

Question

I have a user table, that has 2 foreign keys for results (one for user result, and one for average result). There is one result table for both.

How to map such situation in hibernate? I tried one-to-one mapping, but it don't work. In java, for easy access to results I want something like that:

public class ParticipantData {
    int id;
    DataValues pickedData;
    DataValues averageData;
}

User table:

CREATE TABLE IF NOT EXISTS `participant_data` (
  `participant_data_id` int(11) NOT NULL AUTO_INCREMENT,
  `picked_data_id` int(11) NOT NULL,
  `average_data_id` int(11) NOT NULL,
  PRIMARY KEY (`participant_data_id`),
  KEY `average_data` (`average_data_id`),
  KEY `picked_data` (`picked_data_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;

average_data and picked_data points to data_values_id in results

Result table:

CREATE TABLE IF NOT EXISTS `data_values` (
  `data_values_id` int(11) NOT NULL AUTO_INCREMENT,
  `n1` float NOT NULL,
  `s1` float NOT NULL,
  `x1` float NOT NULL,
  `a` float NOT NULL,
  `b` float NOT NULL,
  PRIMARY KEY (`data_values_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=36407 ;

My hibernate mapping that don't work:

ParticipantData:

<hibernate-mapping>
  <class name="com.mep.model.ParticipantData" table="participant_data">
   <id name="id" type="int" column="participant_data_id" >
   <generator class="increment"/>
  </id>

  <one-to-one name="pickedData" class="com.mep.model.DataValues" cascade="all" constrained="true"/>
  <one-to-one name="averageData" class="com.mep.model.DataValues" cascade="all" constrained="true"/>
 </class>
</hibernate-mapping>

DataValues:

<hibernate-mapping>
    <class name="com.mep.model.DataValues" table="data_values">
        <id name="id" type="int" column="data_values_id">
            <generator class="increment" />
        </id>

        <property name="n1" type="float" column="n1" />
        <property name="s1" type="float" column="s1" />
        <property name="x1" type="float" column="x1" />
        <property name="a" type="float" column="a" />
        <property name="b" type="float" column="b" />

        <one-to-one name="participantData" class="com.mep.model.ParticipantData"
            cascade="all"></one-to-one>
    </class>
</hibernate-mapping>

I will appreciate any help :)

Answer 1

I think that you problem is, that it is not possible to specify optional one-to-one relationships. So Hibernate forces you to specifiy a default value. Have a look at the answer of the following question for a workaround. Optional one-to-one mapping in Hibernate