I've created a UserObject and RoleObject to represent users in my application. I'm trying to use hibernate for CRUD instead of raw JDBC. I've successfully retrieved the information from the data base, but I can not create new users. I get the following error.

```
org.springframework.web.util.NestedServletException: Request processing failed; nested
exception is org.springframework.dao.DataIntegrityViolationException: could not insert: 
[com.dc.data.UserRole]; nested exception is 
org.hibernate.exception.ConstraintViolationException: could not insert: 
[com.dc.data.UserRole]

```

My data base is defined as follows:

Users Table, Authority Table and Authorities table. Authorities table is a join of users and authority.

My hibernate mapping for UserObjec is as follows:

```
  ...
  <set name="roles" table="authorities" cascade="save-update"  lazy="false" >
            <key column="userId" />
            <one-to-many class="com.dc.data.UserRole"/>
            <many-to-many  class="com.dc.data.UserRole" column="authId" />
        </set>
    </class>
   ...

```

UserRole is mapped as follows:

```
<class name="com.dc.data.UserRole" table="authority">
    <id name="id" column="authId">
        <generator class="native" />
    </id>
    <property name="roleName">
        <column name="authority" length="60" not-null="true" />
    </property>
</class>

```

How do I need to change my mapping or Object structure to be able to persist new users?