如何在 Hibernate 查询语言中查询所有具有关联实体的实体？

Question

我很难理解如何查询具有指定类别关联的所有产品。

我可能需要这样的东西

select p.* from product p
inner join product_category pc on p.product_id = pc.product_id
inner join category c on pc.category_id = c.category_id
where c.name = :categoryName;

但在 HQL 中。

Answer 1

假设您使用以下映射：

@Entity
@Table(name = "product")
class Product
{
   @Id
   @Column(name = "product_id")
   private Long id;

   @ManyToMany
   @JoinTable(name = "product_category",
        joinColumns = @JoinColumn(name = "category_id"),
        inverseJoinColumns = @JoinColumn(name = "product_id")
    )
   private List<Category> categories;

   // getters/ setters
}

@Entity
@Table(name = "category")
class Category
{
   @Id
   @Column(name = "category_id")
   private Long id;

   @Column(name = "name")
   private String name;

   // getters/ setters
}

您可以使用以下 HQL：

select p from Product
join fetch p.categories c
where c.name = :categoryName

如何在 Hibernate 查询语言中查询所有具有关联实体的实体？

How can I query all entities that have an associated entity in Hibernate Query Language?

java

orm

hibernate

hql