javax.persistence.EntityManager man = javax.persistence.Persistence.createEntityManagerFactory("PU2").createEntityManager();
          
          EntityTransaction tr= man.getTransaction();
              tr.begin();
              
             Lockdoc lock=new Lockdoc();
             
               
               lock.setDateLock(new Date());
               lock.setIdContactlock(this.globalSettings.getUserSystem());
               lock.setIdPrihodnakl(prihodNLock.getId());
               lock.setPrihodnakl(prihodNLock);
             
             man.persist(lock);
             
             tr.commit();
             
             man.close();

public class Lockdoc implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @Column(name = "id_prihodnakl")
    private Integer idPrihodnakl;
    @Column(name = "date_lock")
    @Temporal(TemporalType.TIMESTAMP)
    private Date dateLock;
    @JoinColumn(name = "id_contactlock", referencedColumnName = "id")
    @ManyToOne
    private Contacts idContactlock;
    @JoinColumn(name = "id_prihodnakl", referencedColumnName = "id", insertable = false, updatable = false)
    @OneToOne(optional = false)
    private Prihodnakl prihodnakl;

  javax.persistence.EntityManager em = javax.persistence.Persistence.createEntityManagerFactory("PU2").createEntityManager();
  EntityTransaction entr=em.getTransaction();
  entr.begin();

Query query=em.createQuery("DELETE FROM Lockdoc st WHERE st.idPrihodnakl= ?1 and st.idContactlock= ?2");
     
    query.setParameter(1, lockD.getIdPrihodnakl());
    query.setParameter(2, globalSettings.getUserSystem()); 


int deleteRecord=query.executeUpdate();

         entr.commit();
         em.close();

Exception Description: Cannot persist detached object [frtree.Lockdoc[ idPrihodnakl=1 ]].