JPA按子集合中最后一个元素的属性进行查询 [英] JPA sorting query by property of last element in child collection

问题描述

说我有以下实体

class Order {

    @Id
    private long id;

    private long orderNo;

    @OneToMany
    @JoinColumn(name="order_id")
    @OrderBy("timeStamp ASC")
    private List<Item> items;
}

class Item {
    @Id
    private long id;

    // e.g. COMPLETED, IN PROGRESS, QUEUED, etc...
    private String status;

    private long timeStamp;

    @ManyToOne
    private Order order;
}

使用JPA，我想返回一个订单列表，该列表按项目列表中最后一个项目的状态进行排序，这是最新的，因为项目是按timeStamp排序的.该怎么办?

Using JPA I want to return a list of Orders that are sorted by the status from the last Item in the items list, which is the most recent one since items is order by timeStamp. How can this be done?

推荐答案

类似，

Select o from Order o join o.items i where i.id = (Select max(timestamp) from Item i2 where i = i2) order by i.status

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