休眠一对多查询

Question

我有以下具有一对多关系的类表

人

 @Entity 
 public class People{ 
     @Id @Column private Integer id;
     @Column(name="FNAME")  private String fName;   
     @Column(name="LNAME")  private String lName;   
     @OnetoMany(targetEntity=Registration.class, mappedBy="pId", cascade.....)  
     private Set<Registrations> registrations;   
     //getters and setters 
  } 

活动

  @Entity
  public class Events{
     @Id @Column private Integer id;   
     @Column(name="NAME")  private String name;
     @Column(name="DATE")  private Timestamp date;
    @OnetoMany(targetEntity=Registration.class, mappedBy="eId", cascade.....)  
    private Set<Registrations> registrations;   
    //getters and setters 
  }

注册

  @Entity
  public class Registrations{
     @Id @Column private Integer id;   
     @Manytoone @JoinColumn(name="pid" ) private Person person;
     @Manytoone @JoinColumn(name="eid" ) private Event event;
  //getters and setters 
  }

所以在用户输入“事件ID”列表时的输入表单中，我需要返回参加这些事件的人员列表。如何为这种类型编写查询？ 到目前为止我有这个..

from Person p join p.registations r where r.event.id in (:eventIdlist)"

但我认为它同时返回人员和重新定义对象。因为当我执行此 List person = query.list() 时，我得到了无法转换的错误。我只需要人员对象列表。

Answer 1

select distinct r.person from Registration r where r.event.id in (:eventIdList)

Answer 2

更简单：

select r.person from Registration r where r.event.id in (:eventIdList)

已编辑评论：要加入其他表格，您可以这样做：

select p
from Person p
where p.registration.event.id in (:eventIdList)
and p.peopleLanguage.language.id in (:languageIdList)