Hibernate entity manager seemed to have a problem with the following attribute in my class:



As indicated in my annotation, the foreign key "course_id" in the association table "students_courses" (created by Hibernate entity manager automatically) is supposed to be non-unique (i.e., unique=false). But Hibernate kept translating it as unique in generating the SQL code as captured below:

create table students_courses (
students_id bigint not null,
courses_id bigint not null,
mapkey bigint,
primary key (students_id, mapkey),
unique (courses_id)
)

This caused the runtime exception for duplicate foreign key courses_id while I was trying to insert a record of another student having the same courses_id=1 as the other student already existed in the database:

[main] Executing batch size: 1
[main] com.mchange.v2.c3p0.impl.NewPooledConnection@7038b9 handling a throwable.
java.sql.BatchUpdateException: Duplicate entry '1' for key 2

The previous student's record was inserted by first adding the course whose courses_id=1 and then added the that student's record in a non-cascade fashion. Hibernate only threw exception during the second addition of another student with the same courses_id. That's because the foreign key courses_id was created as unique in the join table students_courses.

I checked the table definition in the database. It showed the following layout of attribute types in the join table:

mysql> describe students_courses;


Is there a way to alter this behavior in Hibernate entity manager? Or is this just another problem that I will have to bear with?

william


Hibernate version:

hibernate-EntityManager3.3.1.GA

Name and version of the database you are using:

mysql-5.0.45-win32.zip

Debug level Hibernate log excerpt: