如何为多对多关联编写HQL查询

Question

因此，我花了几个小时来尝试为多对多关系编写HQL查询。 对于所有我尝试过的查询，即使阅读了休眠文档也没有任何效果。 有人可以帮我吗？ 先感谢您。

我尝试了内部连接，具有和不具有提取的外部连接。 我认为这个问题可能与香水类中的一对多关系有关。

@Query("FROM Category c INNER JOIN FETCH c.fragrances f WITH c.referencedId = 1")
List<Category> getCatalog();

没有获取/设置者的类别类

@Entity
public class Category extends AbstractEntity {

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

   @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
   @JoinTable(name = "Category_has_Fragrance",
        joinColumns = @JoinColumn(name = "category_id"),
        inverseJoinColumns = @JoinColumn(name = "fragrance_id")
   )
   @OrderBy("name")
   private List<Fragrance> fragrances;

   @Column(name = "referenced_id", nullable = false)
   private int referencedId;
]

没有get / setter的香料类

@Entity
public class Fragrance extends AbstractEntity {

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

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

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "fragrances")
    private Set<Category> categories;

    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "fragrance")
    private List<FragrancedProduct> fragrancedProducts;

    @Column(name = "image_path")
    private String imagePath;
}

Answer 1

尝试这个：

select c from Category c join c.fragrances f where c.referencedId = :id

您可以在此处检查类似的问题： 如何使用HQL，很多很多？