[英]JPQL ManyToMany select
I have a Many To Many relationship between two entities called: Car and Dealership. 我在两个实体之间有一个多对多的关系:汽车和经销商。
In native MySQL I have: 在原生MySQL中我有:
car (id and other values)
dealership (id and other values)
car_dealership (car_id and dealership_id)
And the query I want to make in JPQL is: 我想在JPQL中创建的查询是:
#Select List of cars in multiple dealerships
SELECT car_id FROM car_dealership WHERE dealership_id IN(1,2,3,56,78,999);
What is the proper way to make the JPQL equivalent? 使JPQL等效的正确方法是什么?
My Java method signature is: 我的Java方法签名是:
public List<Car> findByDealership(List<Dealership> dealerships);
I have tried 我努力了
//TOTALLY WRONG QUERY CALL!!!
Query query = em.createQuery("SELECT c FROM Car c WHERE :dealer_ids IN c.dealerships");
List<Long> dealerIds = new ArrayList<Long>();
for(Dealership d : dealerships) {
dealerIds.add(d.getId());
}
query.setParameter(":dealer_ids", dealerIds);
List<Dealership> result = (List<Dealership>) query.getResultList();
return result;
}
Here is my JPA Annotations for such relationship in java: 这是我在java中的这种关系的JPA注释:
@Entity
@Table(name = "car")
public class Car implements Serializable {
//Setup of values and whatnot....
@ManyToMany
@JoinTable(name = "car_dealership", joinColumns =
@JoinColumn(name = "car_id", referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(name = "dealership_id", referencedColumnName = "id"))
private List<Dealership> dealerships;
... other stuff (getters/setters)
}
@Entity
@Table(name = "property")
public class Dealership implements Serializable {
//Setting of values and whatnot
@ManyToMany(mappedBy = "dealerships")
private List<Car> cars;
.... other stuff(getters/setters)
}
EDIT 编辑
I also have tried: 我也尝试过:
Query query = em.createQuery("SELECT c FROM Car c INNER JOIN c.dealerships d WHERE d IN (:deals)");
query.setParameter("deals", dealerships);
Which threw the Error: 哪个扔了错误:
org.eclipse.persistence.exceptions.QueryException
Exception Description: Object comparisons can only use the equal() or notEqual() operators.
Other comparisons must be done through query keys or direct attribute level comparisons.
Expression: [
Relation operator [ IN ]
Query Key dealerships
Base stackoverflow.question.Car
Constant [
Parameter deals]]
select car from Car car
inner join car.dealerships dealership
where dealership in :dealerships
The parameter must be a collection of Dealership instances. 该参数必须是经销商实例的集合。
If you want to use a collection of dealership IDs, use 如果您想使用经销商ID的集合,请使用
select car from Car car
inner join car.dealerships dealership
where dealership.id in :dealershipIds
Remamber that JPQL always use entities, mapped attributes and associations. 请记住,JPQL始终使用实体,映射属性和关联。 Never table and column names. 从不使用表名和列名。
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