Cannot delete or update a parent row - JPA with Hibernate

Question

I have a database in which all of the tables have been generated by Java JPA/Hibernate code. I need to update several tables in my database in a fashion similar to this,

UPDATE Department SET id=100000 WHERE id=0;

Unfortunately this results in the error

ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (departmentuserlink, CONSTRAINT FK96AF44EAB09C41C5 FOREIGN KEY (department_id) REFERENCES department (id))

Here are the Java entities:

@Entity @Table(name="Department") public class Department extends AbstractEntity implements IAbstractEntity { @OneToMany(cascade=CascadeType.ALL, mappedBy="department", fetch=FetchType.EAGER) private Set<DepartmentJobLink> departmentJobs = new HashSet<DepartmentJobLink>(0); //Setters & getters and all that } @Entity @Table(name="edrDepartmentJobLink", uniqueConstraints={@UniqueConstraint(columnNames={"department_id", "job_id"})}) public class DepartmentJobLink extends AbstractEntity implements IAbstractEntity { @ManyToOne(fetch=FetchType.EAGER) @JoinColumn(name="department_id", nullable=false) private Department department; //Setters & getters and all that }

They both have ID's in the superclass. So far it looks like everything else about them works great, just running into trouble with updating the primary key of Department. I would appreciate any advice. Thanks.

matt b · Accepted Answer · 2010-07-22 20:52:56Z

Well, what foreign keys does the table being updated have? Sounds like you cannot change the value of department.id because some other table has a foreign key constraint on it's department_id column pointing to department.id.

This is actually "A Good Thing" since it means your data is reliable.

You need to change your update statement so that you are also updating the department_id column of the affected table along with department.id (as well as any other affected tables), or optionally you could ALTER the foreign key constraint so that changes are cascaded. The syntax to do this will vary with your Database implementation.

This actually doesn't have anything to do with JPA or Hibernate - it's purely a result of foreign-key constraints declared in your database (which may have come from a Hibernate mapping and auto-generating the database schema from a Hibernate schema generator tool, but that is irrelevant now).

So it appears from what you're saying, and from looking at the tables in PhpMyAdmin a bit, that the cascade=CascadeType.ALL in the column annotation doesn't result in cascading updates being set on the actual tables. Do you know if there's a way to add cascading updates to the tables themselves through JPA, or would I be best served by adding them myself when it's required? Thanks for your input. I believe I have a better understanding of what's happening now.
JPA doesn't create tables for you. There may be tools that can auto-generate table definitions based on your JPA annotations/hibernate mappings, but it isn't as if using JPA means the table creation is handled for you. "Cascade" in terms of JPA means something different.

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