On delete set null in hibernate in @OneToMany

Question

I have a Department entity which relations are as follows:

1. Many departments can be in one parent department:

Answer 1

You'll have to set the children's ik_parent_department_id to null explicitly.

Department parentDepartment = (Department) session.load(Department.class, id);
session.delete(parentDepartment);
for (Department child : parentDepartment.getChildren()){
    child.setParentDepartment(null);
} 
session.flush();

With cascading you would only manage to delete child Departments.