Question

商店产品和类别之间存在多对多关系。多个商店有相同/多个产品。每个产品属于多个类别。我想获得具有给定类别ID的特定商店中的产品列表。

        sql = "select shop.products as products from Shop shop" +
                " join shop.products product" +
                " join product.categories category" +
                " where shop.id = :shopId and category.id = :categoryId";

商店有类似的东西：

@ManyToMany(mappedBy = "shops")
private List<Product> products;

产品有：

@ManyToMany
@JoinTable(name = "Products_Categories", joinColumns = {@JoinColumn(name = "Product_ID")},
        inverseJoinColumns = {@JoinColumn(name = "Category_ID")})
private Set<Category> categories;

@ManyToMany
@JoinTable(name = "Shop_Product", joinColumns = {@JoinColumn(name = "Product_ID")},
        inverseJoinColumns = {@JoinColumn(name = "Shop_ID")})
private Set<Shop> shops = new HashSet<>();

并且在类别I中有类似的内容：

@ManyToMany(mappedBy = "categories")
private List<Product> products;

但是，无论提供的类别如何，上述查询的结果集都包含所有数据。

生成SQL

select product6_.id as id1_4_, product6_.calories as calories2_4_, product6_.createdDate as createdD3_4_, product6_.description as descript4_4_, product6_.modifiedDate as modified5_4_, product6_.name as name6_4_, product6_.price as price7_4_ from Shop shop0_
  inner join Shop_Product products1_ on shop0_.id=products1_.Shop_ID
  inner join Products product2_ on products1_.Product_ID=product2_.id
  inner join Products_Categories categories3_ on product2_.id=categories3_.Product_ID
  inner join Categories category4_ on categories3_.Category_ID=category4_.id
  inner join Shop_Product products5_ on shop0_.id=products5_.Shop_ID
  inner join Products product6_ on products5_.Product_ID=product6_.id where
  shop0_.id=? and category4_.id=?

更新：问题是因为生成的sql有额外的连接。检查SQL中的第6行和第7行。这不是必需的。我该如何避免呢？

Answer 1

我通过稍微调整查询来解决问题：

        sql = "select product from Shop shop" +
                " join shop.products product" +
                " join product.categories category" +
                " where shop.id = :shopId and category.id = :categoryId";

使用多对多JPQL的错误结果集

1 个答案: