Deleting a child Object leads to a JDBC Batch Update Exception

Question

When I try to delete a "Course" object, I get this exception:
Referential integrity constraint violation: "FKCE6C075833B16F41: PUBLIC.TEACHER_COURSE FOREIGN KEY(COURSES_ID) REFERENCES PUBLIC.COURSE(ID)" SQL statement: delete from Course where id=?

The "Course" class looks like this:

@Entity
public class Course extends Model {
  @ManyToOne
  public Teacher teacher;
  ...
}

The "Teacher" class looks like this:

@Entity
public class Teacher extends Model {
  @OneToMany(mappedBy="teacher", cascade=CascadeType.ALL)
  public List<Course> courses;
  ...
}

Whenever I try to delete a "Course" from my controller (using the delete() method), I get the exception above. How do I fix it? I've tried various ways of mapping. Do I need to fix the schema of the database somewhere?

Thanks for all the help! This is my first post here, if there's anything I need to make clearer, please let me know!

score 1 · Accepted Answer · edited May 23 '17 at 12:03

Looks to me like you're trying to delete a Course record, but there is still a Teacher record that has a reference to the course you're trying to delete (stored in the TEACHER_COURSE join table). This is normal, because you have defined a bi-directional relationship: a Course knows its Teacher, and a Teacher knows the Course objects that belong to it.

One option would be to simply get rid of the bi-directional relationship if possible (eg. remove the relationship from Teacher to Course by remove the courses list). Another would be to remove the Course instance you want to delete from the courses list first, and then delete it (note: you may have to persist/merge the courses list first before deleting the course so there is no link anymore).

This question on the matter may provide some additional insight.

I tried to remove the Course instance from the list, but that proved to be complicated and I realized I didn't need it, so I removed the relationship. But I need to read up on those JPA docs. Thanks again! — Budgetperson, Jan 28 '12 at 22:24

score 1 · Answer 2 · answered Jan 30 '12 at 03:14

I think that you are mapping the relationship in the inverse direction. You are mapping like course is the Parent side of the relationship, instead of Teacher. From Hibernate docs:

To map a bidirectional one to many, with the one-to-many side as the owning side, you have to remove the mappedBy element and set the many to one @JoinColumn as insertable and updatable to false. This solution is not optimized and will produce some additional UPDATE statements.

@Entity
public class Course extends Model {
    @ManyToOne
    @JoinColumn(name="teacher_id")
    public Teacher teacher;
    ...
}

And Teacher:

@Entity
public class Teacher extends Model {
  @OneToMany(cascade=CascadeType.ALL)
  @JoinColumn(name="teacher_id")
  public List<Course> courses;
  ...
}

Deleting a child Object leads to a JDBC Batch Update Exception

2 Answers2