SqlResultSetMapping

    Query q = em.createNativeQuery(
        "SELECT o.id AS order_id, " +
            "o.quantity AS order_quantity, " +
            "o.item AS order_item, " +
            "i.name AS item_name, " +
        "FROM Order o, Item i " +
        "WHERE (order_quantity > 25) AND (order_item = i.id)",
    "OrderResults");

    @SqlResultSetMapping(name="OrderResults",
        entities={
            @EntityResult(entityClass=com.acme.Order.class, fields={
                @FieldResult(name="id", column="order_id"),
                @FieldResult(name="quantity", column="order_quantity"),
                @FieldResult(name="item", column="order_item")})},
        columns={
            @ColumnResult(name="item_name")}
    )