相关疑难解决方法(0)

是否可以创建一个@Entity不包含主键/ Id 的表(来自JPA注释的Hibernate )？

我知道这不是一个好主意; 表应该有一个主键.

能否帮助我如何使用一个公共连接表连接三个表？我有USER,APPLICATION和ROLE表.我希望将他们的ID加入名为USER_APP_ROLE(user.ID,application.ID,role.ID)的表中.

当我删除Join Many to Many中的Application或Role表时,我的代码正在运行.

我做了以下代码:

User.java

@ManyToMany (targetEntity=Role.class)
@JoinTable(name="USER_APPLICATION_ROLE",
    joinColumns=@JoinColumn(name="USER_ID"),
    inverseJoinColumns=@JoinColumn(name="ROLE_ID"))

private Collection<Role> roles;

@ManyToMany (targetEntity=Application.class)
@JoinTable(name="USER_APPLICATION_ROLE",
    joinColumns=@JoinColumn(name="USER_ID"),
    inverseJoinColumns=@JoinColumn(name="APPLICATION_ID"))
private Collection<Application> applications;

Role.java

@ManyToMany(mappedBy="roles", targetEntity=User.class)
private Collection<User> users = new ArrayList<User>();

Application.java

@ManyToMany(mappedBy="applications", targetEntity=User.class)
private Collection<User> users = new ArrayList<User>();

当我尝试运行以下测试时:

    user.getRoles().add(role1);
    user.getRoles().add(role2);

    role1.getUsers().add(user);
    role1.getUsers().add(user);

    role2.getUsers().add(user);
    role2.getUsers().add(user);

    user.getApplications().add(app1);
    user.getApplications().add(app2);

    app1.getUsers().add(user);
    app2.getUsers().add(user);
      ......

      session.beginTransaction();
      session.save(user);
      session.save(role1);
      session.save(role2);
      session.save(app1);
      session.save(app2);

我收到以下错误:

Hibernate: select seq_cm_user.nextval from dual
Hibernate: select seq_role.nextval from dual
Hibernate: select seq_role.nextval from dual
Hibernate: select seq_application.nextval from dual …