对于两个类/表之间的连接，正确的Hibernate查询语法是什么？

Question

我已经做了几个小时没有成功。对于我从这里记录的其他事件或其他地方的示例中尝试的所有内容，HQL语法在我的方法中似乎总是错误的：

 Session session = sessionFactory.openSession();
    try { 


        Query query = session.createQuery("select p from Person p join p.books where p.personId = :personId").setParameter("personId", personId);

        List<Person> persons = query.list();    
        Person person = persons.get(0);
        Hibernate.initialize(person.getBooks());
        return person;
    }        
    finally {
        session.close();            
    }    

每次Hibernate都会给我一条信息：

@Entity
@Table(name = "PERSON")
public class Person implements Serializable {

// Attributes.    
@Id
@Column(name="PERSON_ID", unique=true, nullable=false)    
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer personId;

@Column(name="NAME", nullable=false, length=50)      
private String name;

@Column(name="ADDRESS", nullable=false, length=100)
private String address;

@Column(name="TELEPHONE", nullable=false, length=10)
private String telephone;

@Column(name="EMAIL", nullable=false, length=50)
private String email;

@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY)     
private List<Book> books;

Entity
@Table(name = "BOOK")
public class Book implements Serializable {

// Attributes.
@Id
@Column(name="BOOK_ID", unique=true, nullable=false)
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer bookId;

@Column(name="AUTHOR", nullable=false, length=50)
private String author;

@Column(name="TITLE", nullable=false, length=50)
private String title;

@Column(name="DESCRIPTION", nullable=false, length=500)
private String description;

@Column(name="ONLOAN", nullable=false, length=5)
private String onLoan;

@ManyToOne
@JoinColumn(name="person_Id")    
private Person person;

select person0_.PERSON_ID as PERSON_I1_1_0_, book2_.BOOK_ID as BOOK_ID1_0_1_, person0_.ADDRESS as ADDRESS2_1_0_, person0_.EMAIL as EMAIL3_1_0_, person0_.NAME as NAME4_1_0_, person0_.TELEPHONE as TELEPHON5_1_0_, book2_.AUTHOR as AUTHOR2_0_1_, book2_.DESCRIPTION as DESCRIPT3_0_1_, book2_.ONLOAN as ONLOAN4_0_1_, book2_.person_Id as person_I6_0_1_, book2_.TITLE as TITLE5_0_1_, books1_.PERSON_PERSON_ID as PERSON_P1_1_0__, books1_.books_BOOK_ID as books_BO2_2_0__ from PERSON person0_ left outer join PERSON_BOOK books1_ on person0_.PERSON_ID=books1_.PERSON_PERSON_ID left outer join BOOK book2_ on books1_.books_BOOK_ID=book2_.BOOK_ID where person0_.PERSON_ID=?

使用如下所示的查询：

Query query = session.createQuery("select from Person as p left join fetch p.books where p.personId = :personId").setParameter("personId", personId);

堆栈跟踪为：

Your page request has caused a QuerySyntaxException: unexpected token: from near line 1, column 8 [select from library.model.Person as p left join fetch p.books where p.personId = :personId] error:

 org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:91)

Answer 1

使用联接提取急切地加载链接的集合：

FROM Person as p LEFT JOIN FETCH p.books WHERE p.personId = :personId