ManyToMany problem: removing referenced records

[nico.ben]

Hi,
I am working with ManyToMany annotation and I cannot obtain the behaviour I'd like to. I need for this forum's help.

I have these tables:

SkillTypes:
id_skill_type
...


Operations:
id_operation
...


R_operations_skills:
id_r_operation_skill PK
id_operation FK
id_skill_type FK


In my 2 entity beans (I don't have a EJB for the relation table R_operations_skills) I used these annotations:

Operation.java

@ManyToMany(cascade={CascadeType.REFRESH, CascadeType.PERSIST}, fetch=FetchType.LAZY)
 @JoinTable(name="r_operations_skills",
 joinColumns=@JoinColumn(name="id_operation"),
 inverseJoinColumns=@JoinColumn(name="id_skill_type"))
 @OrderBy("description")
 public List<SkillType> getSkillTypes() {
 return skillTypes;
 }

SkillType.java

@ManyToMany(cascade={CascadeType.REFRESH, CascadeType.PERSIST}, fetch=FetchType.LAZY)
 @JoinTable(name="r_operations_skills",
 joinColumns=@JoinColumn(name="id_skill_type"),
 inverseJoinColumns=@JoinColumn(name="id_operation"))
 @OrderBy("description")
 public List<Operation> getOperations() {
 if(operations == null) {
 operations = new ArrayList<Operation>();
 }
 return this.operations;
 }

My problem is that deleting a skill which has relations with operations, the skill is removed from SkillTypes and also records in the relation table are deleted.
I exptected that I cannot delete a skillType used in the relation.
Could you please suggest me how to solve my problem?

Thank u
Nico