Question

几天前，一位同事提出了以下问题：Order and group by with one column

已解决。一个简单干净的查询，非常酷。该解决方案似乎是值得的，除了我们需要在JPA中实现它。

由于JPA在JOIN中不接受子查询，因此我们必须将其作为nativeQuery进行，但是这样做会遇到分页问题，因为JPA不会将其与本地查询结合在一起。 https://docs.spring.io/spring-data/jpa/docs/1.8.0.M1/reference/html/

本地查询@Query批注允许执行本地查询通过将nativeQuery标志设置为true。请注意，我们目前还没有支持对本机查询执行分页或动态排序因为我们必须处理声明的实际查询，所以我们无法做对于本机SQL来说确实如此。

我们不知道该如何继续。

我们必须做的：我们拥有一系列包含电话号码，用户和日期的记录，每个用户已经可以拨打N次。我们需要获取按电话号码分组并按每组号码的最新日期进行排序（DESC）的所有记录。

例如：

使用此数据：

+--------------+---------------------+-------------+---------------+
| phone_number | registered          | name        | first_surname |
+--------------+---------------------+-------------+---------------+
|    222005001 | 2019-05-10 10:01:01 | Alvaro      | Garcia        |
|    222004001 | 2019-05-13 16:14:21 | David       | Garcia        |
|    111003001 | 2019-05-13 16:14:43 | Roberto     | Martin        |
|    111001000 | 2019-05-13 16:14:50 | Juan Manuel | Martin        |
|    111001000 | 2019-05-13 16:14:50 | Maria       | Alonso        |
|    111001000 | 2019-05-13 16:14:50 | Roberto     | Martin        |
|    333006001 | 2019-05-13 16:14:55 | Benito      | Lopera        |
|    123456789 | 2019-05-13 16:15:00 | NULL        | NULL          |
|    987654321 | 2019-05-13 16:15:08 | NULL        | NULL          |
|    123456789 | 2019-05-13 16:15:13 | NULL        | NULL          |
|    666999666 | 2019-05-13 16:15:18 | NULL        | NULL          |
|    454545458 | 2019-05-13 16:15:27 | NULL        | NULL          |
|    333006001 | 2019-05-13 16:23:36 | Benito      | Lopera        |
|    987654321 | 2019-05-13 16:23:46 | NULL        | NULL          |
|    666999666 | 2019-05-13 16:23:50 | NULL        | NULL          |
|    454545458 | 2019-05-13 16:23:55 | NULL        | NULL          |
|    666999666 | 2019-05-13 16:24:03 | NULL        | NULL          |
|    222004001 | 2019-05-13 16:24:10 | David       | Garcia        |
+--------------+---------------------+-------------+---------------+

像这样对它们排序：

+--------------+---------------------+-------------+---------------+
| phone_number | registered          | name        | first_surname |
+--------------+---------------------+-------------+---------------+
|    222004001 | 2019-05-13 16:24:10 | David       | Garcia        |
|    222004001 | 2019-05-13 16:14:21 | David       | Garcia        |
|    666999666 | 2019-05-13 16:24:03 | NULL        | NULL          |
|    666999666 | 2019-05-13 16:23:50 | NULL        | NULL          |
|    666999666 | 2019-05-13 16:15:18 | NULL        | NULL          |
|    454545458 | 2019-05-13 16:23:55 | NULL        | NULL          |
|    454545458 | 2019-05-13 16:15:27 | NULL        | NULL          |
|    987654321 | 2019-05-13 16:23:46 | NULL        | NULL          |
|    987654321 | 2019-05-13 16:15:08 | NULL        | NULL          |
|    333006001 | 2019-05-13 16:23:36 | Benito      | Lopera        |
|    333006001 | 2019-05-13 16:14:55 | Benito      | Lopera        |
|    123456789 | 2019-05-13 16:15:13 | NULL        | NULL          |
|    123456789 | 2019-05-13 16:15:00 | NULL        | NULL          |
|    111001000 | 2019-05-13 16:14:50 | Maria       | Alonso        |
|    111001000 | 2019-05-13 16:14:50 | Roberto     | Martin        |
|    111001000 | 2019-05-13 16:14:50 | Juan Manuel | Martin        |
|    111003001 | 2019-05-13 16:14:43 | Roberto     | Martin        |
|    222005001 | 2019-05-10 10:01:01 | Alvaro      | Garcia        |
+--------------+---------------------+-------------+---------------+

可以通过以下查询完成：

SELECT c.phone_number, c.registered, cl.name, cl.first_surname
FROM callers cl
    INNER JOIN callers_phones cp ON cl.caller_id = cp.caller_id
    RIGHT OUTER JOIN calls c ON c.phone_number = cp.phone_number
    JOIN (
        SELECT phone_number, MAX(registered) AS registered
        FROM calls
        GROUP BY phone_number) aux_c ON aux_c.phone_number = c.phone_number
WHERE c.answered = FALSE
    AND (null is null or null is null or c.registered between null and null)
    AND (null is null or c.phone_number = null)
    AND (null is null or cl.caller_id = null)
ORDER BY aux_c.registered DESC, c.registered DESC

这些是表格：

CREATE TABLE callers
(
    caller_id int NOT NULL UNIQUE AUTO_INCREMENT,
    name varchar(50) NOT NULL,
    first_surname varchar(50) NOT NULL,
    CONSTRAINT callers_pkey PRIMARY KEY (caller_id)
);

CREATE TABLE callers_phones
(
    phone_id int NOT NULL UNIQUE AUTO_INCREMENT,
    caller_id int NOT NULL,
    phone_number int NOT NULL,
    CONSTRAINT callers_phones_pkey PRIMARY KEY (phone_id)
);

ALTER TABLE callers_phones
    ADD CONSTRAINT callers_phones_fkey_callers FOREIGN KEY (caller_id)
    REFERENCES callers (caller_id);

CREATE TABLE calls
(   
    call_id int NOT NULL UNIQUE AUTO_INCREMENT,
    phone_number int NOT NULL,
    answered boolean NOT NULL DEFAULT false,
    registered datetime NOT NULL,
    CONSTRAINT calls_pkey PRIMARY KEY (call_id)
);

问题在于我们必须在JPA中使用分页来实现它，但是子查询在JOIN子句中不起作用，分页在nativeQuery中不起作用。

这是我们所做的：

@Entity：

import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.NamedNativeQuery;
import javax.persistence.SqlResultSetMapping;

@SqlResultSetMapping (name = "MissedCallResult",
        entities = {
                     @EntityResult (entityClass = MissedCallEntity.class,
                             fields = {
                                        @FieldResult (name = "callId", column = "id"),
                                        @FieldResult (name = "phoneNumber", column = "pH"),
                                        @FieldResult (name = "registered", column = "reg"),
                                        @FieldResult (name = "callerName", column = "cN"),
                                        @FieldResult (name = "callerFirstSurname", column = "cFS")
                             })
        })
@NamedNativeQuery (name = "findMissedCalls",
        query = "select c.call_id as id, c.phone_number as pH, c.registered as reg, cl.name as cN, cl.first_surname as cFS "
                + "from callers cl "
                + "    inner join callers_phones cp on cl.caller_id = cp.caller_id "
                + "    right outer join calls c on c.phone_number = cp.phone_number "
                + "    join (select c2.phone_number, MAX(c2.registered) as registered "
                + "        from calls c2 "
                + "        group by c2.phone_number) aux_c on aux_c.phone_number = c.phone_number "
                + "where c.answered = false "
                + "    and (:startDate is null or :endDate is null or c.registered between :startDate and :endDate) "
                + "    and (:callerId is null or cl.caller_id = :callerId) "
                + "    and (:phoneNumber is null or c.phone_number = :phoneNumber) "
                + "order by aux_c.registered desc, c.registered desc",
        resultSetMapping = "MissedCallResult")
@Entity
public class MissedCallEntity
{
    @Id
    private Integer callId;
    private Integer phoneNumber;
    private Date registered;
    private String callerName;
    private String callerFirstSurname;
    private String callerSecondSurname;

...

}

@存储库：

import java.util.Date;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;

import es.panel.domain.MissedCallEntity;

@RepositoryRestResource (path = "missedCalls", collectionResourceRel = "missedCalls")
public interface MissedCallRepository extends PagingAndSortingRepository<MissedCallEntity, Integer>
{
    @Query (nativeQuery = true, name = "findMissedCalls")
    Page<MissedCallEntity> findMissedCalls(@Param ("startDate") Date startDate,
                                           @Param ("endDate") Date endDate,
                                           @Param ("callerId") Integer callerId,
                                           @Param ("phoneNumber") Integer phoneNumber,
                                           Pageable page);
}

在@Service中：

public Page<MissedCallEntity> getMissedCalls(Date startDate,
                                                 Date endDate,
                                                 Integer callerId,
                                                 Integer phoneNumber,
                                                 int actualPage,
                                                 int limit)
    {
        Page<MissedCallEntity> calls = mcRepository.findMissedCalls(
                startDate, endDate, callerId, phoneNumber, PageRequest.of(1, 5));

        return calls;
    }

谢谢！

Answer 1

一个非常简单的解决方案是根据您的查询创建一个数据库视图，以获取计算值，即计数和最大值等。

您可以使用JPA {{1}}批注将其映射到相关实体，该批注使您可以将实体映射到多个表（或视图）。

在这里，您可以像使用其他任何字段一样使用标准JPA / spring数据功能进行排序和过滤，并且几乎可以删除所有已编写的代码。

我将进一步详细说明，但是您要达到的目标还不是很清楚：您在询问的是您尝试的解决方案，而不是问题本身。 MissedCall也不是实体。系统中的实体是用户，呼叫，电话等。

如何使用nativeQuery和Spring PagingAndSortingRepository在JPA中分页查询

1 个答案: