JPA entity has no primary key?

Question

I have an Entity class:

@Entity
@Table(name=\"CMC_MAP_SERVER_INFO\")
@NamedQuery(name=\"CmcMapServerInfo.getMapServer\", query=\"SELECT c FROM CmcMapServerIn         


        

Answer 1

Every entity object in the database is uniquely identified. An alternate way to represent a table without a primary key is to use a composite primary key using all its columns, or some of them representing a candidate key:

@Entity
public class TableWithoutId {
    @EmbeddedId EmbeddableTableWithoutId id;

    /* Getters an Setters... */

    //Here you can implement @Transient delegates to the Getters an Setters of "id".
}

@Embeddable
Class EmbeddableTableWithoutId {
    int columnA;
    long columnB;
    /* Getters an Setters... */
}

Maybe you will have problems with [Select By Id]:

entityManager.find(TableWithoutId.class, id);//it can throws NonUniqueResultException or anything like that...

Take care and be happy!!!