JPA一对一映射在未找到子实体时创建多个查询

@Entity
public class ParentEntity {
    @Id
    private Long id;

    @OneToOne(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
    private ChildEntity child;

    // 其他属性和方法
}

@Entity
public class ChildEntity {
    @Id
    private Long id;

    @OneToOne
    @JoinColumn(name = "parent_id")
    private ParentEntity parent;

    // 其他属性和方法
}

public ParentEntity findParentEntity(Long parentId) {
    EntityManager em = // 获取EntityManager对象
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<ParentEntity> query = cb.createQuery(ParentEntity.class);
    Root<ParentEntity> root = query.from(ParentEntity.class);
    query.select(root);

    // 添加查询条件
    query.where(cb.equal(root.get("id"), parentId));

    ParentEntity parent = em.createQuery(query).getSingleResult();

    // 判断子实体是否为空
    if (parent.getChild() == null) {
        // 创建多个查询
        CriteriaQuery<ChildEntity> childQuery = cb.createQuery(ChildEntity.class);
        Root<ChildEntity> childRoot = childQuery.from(ChildEntity.class);
        childQuery.select(childRoot);
        childQuery.where(cb.equal(childRoot.get("parent"), parent));

        List<ChildEntity> children = em.createQuery(childQuery).getResultList();
        parent.setChild(children.isEmpty() ? null : children.get(0));
    }

    return parent;
}