@Entity
@Table(name = "Benutzer")
public class User implements Serializable
{ private long mSid;
 private long mMandantID;
 private String mId;

 public User() { super(); }
 public String getId() { return mId; }
 public void setId(String pId) { mId = pId; }
 @Id @GeneratedValue(strategy=GenerationType.AUTO)
 public long getSid() { return mSid; }
 public void setSid(long pSid) { mSid = pSid; }
 public long getMandantID() { return mMandantID; }
 public void setMandantID(long pMandantID) { mMandantID = pMandantID; }
}

List<User> erg = (List<User>) em.createQuery(
"from User where (Id = :uid) and (pwd=:pwd) and (mandantID=:mandantid)")
.setParameter ("uid", pUserName).setParameter ("pwd", pPwd).setParameter ("mandantid", lMandantID).getResultList();