如何在jpa中查询父表时从子表中获取字段

@Entity
public class Parent {
    @Id
    private Long id;
    
    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "child_id")
    private Child child;
    
    // 省略其他字段和方法
}

@Entity
public class Child {
    @Id
    private Long id;
    
    private String field;
    
    // 省略其他字段和方法
}

String jpql = "SELECT p FROM Parent p JOIN FETCH p.child";
List<Parent> parents = entityManager.createQuery(jpql, Parent.class).getResultList();

@Entity
public class Parent {
    @Id
    private Long id;
    
    @OneToMany
    @JoinColumn(name = "parent_id")
    private List<Child> children;
    
    // 省略其他字段和方法
}

@Entity
public class Child {
    @Id
    private Long id;
    
    private String field;
    
    // 省略其他字段和方法
}

String jpql = "SELECT p FROM Parent p JOIN FETCH p.children";
List<Parent> parents = entityManager.createQuery(jpql, Parent.class).getResultList();

@Entity
public class Parent {
    @Id
    private Long id;
    
    @ManyToMany
    @JoinTable(name = "parent_child",
               joinColumns = @JoinColumn(name = "parent_id"),
               inverseJoinColumns = @JoinColumn(name = "child_id"))
    private List<Child> children;
    
    // 省略其他字段和方法
}

@Entity
public class Child {
    @Id
    private Long id;
    
    private String field;
    
    // 省略其他字段和方法
}

String jpql = "SELECT p FROM Parent p JOIN FETCH p.children";
List<Parent> parents = entityManager.createQuery(jpql, Parent.class).getResultList();