Question

@Entity 
public class Person{

    private String firstName;
    private String lastName;

    @OneToMany(mappedBy="person" , fetch= FetchType.LAZY)
    private Set<Certificate> certificates;
}


@Entity 
public class Certificate{

    private String courseName;

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

}

拥有实体class(Person)，其中包含使用@OneToMany映射的相关实体（证书）的集合（集合），如上所述。现在我必须抓取all Persons having certificate.courseName IN ("OCPJP", "OCPWCD").

在Simple SQL中，我的查询将是这样的。

select distinct p.firstName, p.lastName from Person p join Certificate c on p.Id = c.person_Id
where c.courseName IN ("OCPJP", "OCPWCD")

如何在JPQL中获得类似的输出？

Answer 1

这样的查询可以写成如下：

SELECT DISTINCT(c.person) FROM Certificate c WHERE c.courseName IN (:coursenames)

完整示例：

List<String> courseNames = Arrays.asList("OCPJP", "OCPWCD");

List<Person> result = em.createQuery(
        "SELECT DISTINCT(c.person) " +
        "FROM Certificate c " +
        "WHERE c.courseName IN (:coursenames)", Person.class)
        .setParameter("coursenames", courseNames)
        .getResultList();

JPQL，其中条件设置为值列表

1 个答案: