What kind of associations should I configure ? (I've 2 ideas: create one: many-to-many or two: one-to-many)

In my situation I've 3 tables in database:

a) user: - table of Users
user_id name
1______jack
2______mary
3______zigi
so there are 3 users in database

b) role: - table of Roles
role_id name
1______admin
2______editor
so there are 2 roles in database

c) user_role - association table from User to Role and from Role to User
user_id role_i
1______1
2______2
3______1
3______2
so user "jack" is "admin", "mary" is "editor", but "zigi" is "admin" and "editor"

So every user belongs to one or more roles in some system.

What I need are:

I) when User (with some user_id) or Role (with some role_id) is removed from database: session.delete(User) or session.delete(Role) - the associations in table (c) which belond to given User or Role are also removed, but only the associations, not object on the second end of associations for exapmle, if I remove User whith user_id 3 the action made in database are: removing row from table (a) with user_id = 3 and remove all rows from table (c) whit rows user_id = 3 and don't remove any row from table (b)

II) when we add or remove some user's role for example whe don't whant any more that "zigi" (user_id = 3) could be admin I whant to remove this only from association table (c), so the action made in database is only to remove from table (c) all rows with user_id = 3 and don't remove any row from table (b) and talbe (a)


Hibernate version:
3.0

Name and version of the database you are using:
MySQL 4.1.15

Sounds like many to many to me with users having a collection of roles and vice versa. When you delete associations (scenario II), you just modify the Collections.

E.g.

Thnx - everything works great :) Hibernate is realy powerfull :)