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javahibernateormhql

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

I'm struggling to understand how can I query all products that have specified category association. enter image description here

I might need something like this

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;

but in HQL.

Solution

  • Assuming that you use the following mapping:

    @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
}

    you can use the following HQL:

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