Question

I have the following tables:

USER
    ID VARCHAR(32) INTEGER NOT NULL

ROLE
    ID INTEGER NOT NULL

USERROLE /*Many to Many*/
    USER_ID VARCHAR(32) NOT NULL
    ROLE_ID INTEGER NOT NULL

and I’m using annotations to Map the DB Tables to my Classes.

/* Mapping for USER table */
@Entity
@Table (name="USER")
public class User{
    @Id
    @Column (name="ID")
    private String id;

    @ManyToMany 
    @JoinTable (name="USERROLE", joinColumns = {@JoinColumn (name="USER_ID")}, 
            inverseJoinColumns = {@JoinColumn (name="ROLE_ID")})
    @LazyCollection (LazyCollectionOption.FALSE)
    private List<Role> roles;
}

/* Mapping for ROLE table */
@Entity
@Table (name="ROLE")
public class Role {
    @Id
    @Column (name="ID")
    private int id;

}

Now I would like to do a query that Joins ROLE and USERROLE tables so that i could get those ROLEs that has user assigned to it.

–EDIT

I have the Role.id, and I want to check whether this Role is being referenced in the USERROLE table. in native SQL, I would do it this way:

SELECT DISTINCT A.* from ROLE A INNER JOIN USERROLE B 
WHERE A.ID = B.ROLE_ID AND A.ID = ?;

how to do it in hibernate using HibernateTemplate?

Answer 1

It’s pretty easy:

select role from User user inner join user.roles role where user.id = :userId

Or even simpler, without any query:

User user = (User) session.get(User.class, userId);
return user.getRoles();

EDIT : to know if a given role is referenced by at least one user, you can use the following query, which is very similar to your SQL query:

select distinct role from User user 
inner join user.roles role 
where role.id = :roleId