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Hi i 'm new to the Hibernate and i 'm trying different kind of mappings
When i 'm doing many-to-many mapping, i 'm not able to insert the data in Intermediate table( consist of both the tables primary keys)

I 'm dong many-to-many mapping for Employee and Project.

EMPLOYEE Table consist of EMPID,NAME
PROJECT Table consist of PROID, PROJECT_NAME
Mapping table ( EMP_PROJECT ) consist of EMPID, PROID

my mappinc xmls

Hibernate version:3.0

Mapping documents:

Mapping for Employee
<hibernate-mapping package="mapping/many2many" auto-import="false">
<class name="Employee" table="EMPLOYEE" lazy="true">
<id name="empId" column="EMPID">
<generator class="increment"/>
</id>
<property name="name" column="NAME"/>
<set name="projects" table="EMP_PROJECT" cascade="all" inverse="true">
<key column="EMPID"/>
<many-to-many class="Project" column="PROID">
</many-to-many>
</set>

</class>
</hibernate-mapping>

Mapping for Project
<hibernate-mapping package="mapping/many2many" auto-import="false">
<class name="Project" table="PROJECT" lazy="true">
<id name="proId" column="PROID">
<generator class="increment"/>
</id>
<property name="project_name" column="PRO_NAME"/>
<set name="employee" table="EMP_PROJECT" cascade="all" inverse="true">
<key column="PROID"/>
<many-to-many class="Employee" column="EMPID">
</many-to-many>
</set>
</class>
</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():
txn = ses.beginTransaction();
Employee emp = new Employee();
emp.setName("Name1");

Employee emp2 = new Employee();
emp2.setName("Name2");

Project project2 = new Project();
project2.setProject_name("Project");
project2.setItem(emp);
project2.setItem(emp2);

ses.save(project2);
txn.commit();



Name and version of the database you are using:

HSQLDB server 1.7.1

The generated SQL (show_sql=true):
Hibernate: insert into PROJECT (PRO_NAME, PROID) values (?, ?)
Hibernate: insert into EMPLOYEE (NAME, EMPID) values (?, ?)
Hibernate: insert into EMPLOYEE (NAME, EMPID) values (?, ?)

Hi!
The only thing I noticed is that you have repeated in both mappings. Inverse tells hibernate to ignore that collection changes, meaning that it will commit changes to the database only if there are changes in the collection without the inverse property set to true.

What you should do, if adding an employee to the project implies that the new employee should have a reference to the project it now belongs to, is to force the "double reference". For example:



And do the same thing in the Employee class.

If this doesn't work, maybe you should post your java code to see if there's something strange in it.

Good luck!