"could not extract ResultSet" 在 JPQL GROUP BY 查询中

Question

在带有 Spring Data JPA 的 Spring Boot 1.5 应用程序中，我有一个 TDR table 像：

     Table TDR
-----------------------
id | c_id | m_id | p_id
 1 |   1  |    1 |    1
 2 |   1  |    1 |    2
 3 |   2  |    1 |    1
 4 |   2  |    1 |    2
 5 |   3  |    1 |    1

我需要在其中找到按 m_id 和 p_id 分组的最后记录。使用 PostgreSQL SQL，我使用 MAX 聚合函数执行此操作：

SELECT t.id, t.c_id, t.m_id, t.p_id
FROM (
  SELECT MAX(id) AS id, m_id, p_id 
  FROM tdr
  WHERE m_id = 1                      -- <<< parameterized below
  GROUP BY m_id, p_id
  ) m JOIN tdr t ON t.id = m.id

哪个returns正确记录：

     Table TDR
-----------------------
id | c_id | m_id | p_id
 4 |   2  |    1 |    2
 5 |   3  |    1 |    1

由于 GROUP BY 不包含 c_id，因此 SQL 结构为 correlated sub-query and matched with a join (see this question 以获取详细信息）。

我想用这个 Lombok @Data 实体将这个 SQL 转换为 JPQL：

@Data
@Entity
@Table(name = "TDR")
public class TDR implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(nullable = false)
    private Long id;

    @ManyToOne(optional=false, cascade = { CascadeType.ALL })
    @JoinColumn(name="m_id")
    private M m;

    @ManyToOne(optional=false, cascade = { CascadeType.ALL })
    @JoinColumn(name="p_id")
    private P p;

    @ManyToOne(optional=false, cascade = { CascadeType.ALL })
    @JoinColumn(name="c_id")
    private C c;
}

但是我的 JPQL 用于具有参数化 m ID (:m_id) 的相关子查询：

SELECT t FROM TDR t WHERE t.id in (
  SELECT MAX(t.id) AS id, t.m, t.p FROM TDR t WHERE t.m = :m GROUP BY t.m, t.p
  )

导致此错误：

org.springframework.dao.InvalidDataAccessResourceUsageException: could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet
   // at ...
Caused by: org.hibernate.exception.SQLGrammarException: could not extract ResultSet
   // at ...
Caused by: org.postgresql.util.PSQLException: ERROR: subquery has too many columns

Answer 1

让我突然想到的是你的第一个 SELECT:

SELECT FROM

...未说明您选择的列

Answer 2

Select 只是关联子查询中的连接列：

SELECT t FROM TDR t WHERE t.id in (
  SELECT MAX(t.id) FROM TDR t WHERE t.m = :m GROUP BY t.m, t.p
  )

ObjectDB GROUP BY article was helpful as was this question.

"could not extract ResultSet" 在 JPQL GROUP BY 查询中

"could not extract ResultSet" in JPQL GROUP BY query

java

postgresql

jpa

jpql

spring-data-jpa