Hi,
I've just begun to explore the use of table-per-subclass mapping strategy via the joined-subclass element. Here's my set-up.
I have 2 POJO classes as follows:
1. User, with fields id and name, where id is the identity key.
2. Employee, which is a subclass of User with additional fields, employeeID and department.
I'm using SQL Server 2000, and am using Eclipse development environment. Here's my mapping configuration for the User class:-
Code:
<class name="User" table="MM_USERS">
<id name="id" column="id" type="int" unsaved-value="null" length="5">
<generator class="native"/>
</id>
<property name="name" column="name" type="string" length="50" not-null="true"/>
<many-to-one name="community" column="communityID" not-null="false" class="Community" cascade="all" unique="true"/>
<set name="memberships" table="MM_USERGROUPLINKS" cascade="none" order-by="name asc" where="" >
<key column="userID" />
<many-to-many class="Group" column="groupID" />
</set>
<joined-subclass name="Employee" table="MM_EMPLOYEE">
<key column="personID"/>
<property name="employeeID" column="employeeID" type="string" length="10" not-null="false" />
<property name="department" column="department" type="string" length="30" not-null="false" />
</joined-subclass>
</class>
What I then did was to insert a test Employee via a standalone Hibernate-based Java application which I wrote, and this succeeded.
Then I tried to do the following HQL, and my Eclipse console shows that this is the query generated by Hibernate:
Code:
select u from User as u where u.id = 1
Hibernate: select user0_.id as col_0_0_ from MM_USERS user0_ where user0_.id=?
Hibernate: select user0_.id as id0_, user0_.name as name0_0_, user0_.communityID
as communit3_0_0_, user0_1_.employeeID as employeeID2_0_, user0_1_.department a
s department2_0_, case when user0_1_.personID is not null then 1 when user0_.id
is not null then 0 end as clazz_0_ from MM_USERS user0_ left outer join MM_EMPLO
YEE user0_1_ on user0_.id=user0_1_.personID where user0_.id=?
which is spot on.
However when I tried the following query, I got the results as follows:
Code:
select u from Employee as u where u.id = :id
Hibernate: select employee0_.personID as col_0_0_ from MM_EMPLOYEE employee0_ in
ner join MM_USERS employee0_1_ on employee0_.personID=employee0_1_.id where empl
oyee0_.personID=?
which is wrong since it didn't return all the fields for employee, but only returned the id.
Any ideas what I'm doing wrong here?
Thanks!
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