Hibernate 3.2;
Database: mysql 5.1

[b]mysql tables::[/b]

student;

student_id int(10)
utid varchar(20)
name varchar(20)
-------------------------
essay;

essay_id int(10)
title varchar(100)
assign_id int(10)
grade_letter varchar(2)
grade_deci float(4,2)
corrected varchar(3)
-------------------------------
essay_x_student;

essay_x_student_id int(10)
essay_id int(10)
student_id int(10)



[b]Mapping documents: essay.hdb.xml[/b]
.....
<hibernate-mapping package="marker.test">
<class name="EssayTest" table="essay">
<id name="essayId" type="int" column="essay_id">
<generator class="increment" />
</id>

<set name="students" table="essay_x_student">
<key column="STUDENT_ID" not-null="true"/>
<one-to-many class="marker.bean.Student" />
</set>

<property name="title" ......
......
</class>
</hibernate-mapping>


[b]Problem[/b]
this should be a most routine problem but I can't find a answer through
several books and tutorials.

above there is a table for students, one for essays and a cross_table
to link essays and students as in my case there might be more than student for a given essay.

I've a bean TestEssay and I'd to select all TestEssay objects from the database
and have the Student field which is a set also populated with the Set of Students for each TestEssay. ( private Set students = new HashSet () ;)

query in Hibernate:
HibUtil.getCurrentSession().createQuery("from EssayTest").list();

does yield TestEssay objects; but the TestObject with essay_id = 0
also has a Student object whose student_id = 0;

which is incorrect!

mysql query:
select e.title, e.essay_id, s.student_id, s.name
from essay_x_student x join essay e on e.essay_id = x.essay_id
join student s on x.student_id = s.student_id where e.essay_id = 0

from the mysql command line yields the correct result;

but this same query in Hibernate yields the same result as the query above.

the mapping file is taken directly from tutorials I've been reading
as have the queries;

is there another setting in the mapping file to correctly associate student objects with their essay object, or perhaps a different query?

any assistance would be greatly appreciated.

thank you

Can you be more clear on the quoted text?

Also from your post you say ur mapping file has


The above mapping snippet says - "relate essay with essay_x_student using the student_id"... But I guess it should be
"relate essay with essay_x_student using the essay_id column"
i.e.,

I found the problem:

the mapping is actually many-to-many: hence the cross table;
so essay.hbm.xml should include:

<set name="students" table="essay_x_student">
<key column="ESSAY_ID" not-null="true"/>
<many-to-many column="STUDENT_ID" class="marker.bean.Student" />
</set>

thank you,