EJB and many-to-many relationship

Question

I write two CMP Beans userBean and roleBean with many-to-many relationship
userBean:
  cmp fields: id,name
  cmr fields: userRoles
roleBean:
   cmp fields: id,rolename
   cmr fields: usersinroleIn database I have 3 tables:
USER( ID NUMBER PK,NAME CHAR);
  ROLE( ID NUMBER PK,ROLENAME char);
  USER_ROLE( (USERID FK(USER.ID), ROLEID FK(ROLE.ID)) PK);in sun-cmp-mappings.xml I add cmp fields mapping,
in userBean and roleBean I add secondary table USER_ROLE
then I add CMR mappings to userBEan nd roleBean
ufter deploying of EJB.jar
in client i wrote:
userBeanLocalHome lh=lookupUser();
lh.create(new java.math.BigDecimal(5),'username');when i run client exception occurs in server log I see:
TransactionRollbackException because Container try to insert into USER_ROLE
values(5(userid),null(roleid)) but user have no roles
in that situation how can I create user without any roles?
thanx!

Answer 1

FaraPooyan, I think about this but it is not good idea because it makes 1-n:1-m relationship.
but I whant 0-n:0-m relationship
I resolve this problem by removing secondary table from sun-cmp-entitymappings.xml
So it works good, but now i dont understand: when i need secondary table mapping if they are not needed for many-to-many relationships