JPA中一对多的子查询过滤器总和

Question

我有 2 个实体：

@Entity
class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Set<Contract> contracts= new HashSet<>();
}

和

@Entity
class Contract {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    private Integer numberOfClaims;
}

现在我想构建一个 javax.persistence.criteria.Predicate 来查找 numberOfClaims 大于 x 的所有订单。

Answer 1

尝试：

select o from Order o where
(select sum(c.numberOfClaims) from o.contracts c) > x

请参阅以下 cmobilecom-jpa 开发人员指南中的一些相关子查询示例：

https://cmobilecom.com/docs/jpa/latest/devguide/index.html

使用条件API：

（参考“子查询”一章的“关联到根”部分）

CriteriaQuery<Order> criteriaQuery = criteriaBuilder.createQuery(Order.class);
Root<Order> root = criteriaQuery.from(Order.class);
criteriaQuery.select(root);
criteriaQuery.distinct(true);

// Subquery: correlate the root of parent query
Subquery<Integer> subquery = criteriaQuery.subquery(Integer.class);
Root<Order> subqueryRoot = subquery.correlate(root);
Join<Order, Contract> contracts = subqueryRoot.join("contracts");
subquery.select(criteriaBuilder.sum(contracts.get("numberOfClaims")));

Predicate restriction = criteriaBuilder.greaterThan(subquery, x);
criteriaQuery.where(restriction);

JPA中一对多的子查询过滤器总和

Subquery filter sum with one to many in JPA

java

hibernate

jpa

jpql

spring-data-jpa