Java 如何使用 Hibernate 和 Spring-boot 从 JPA 查询返回 SUM？
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How do I Return SUM from JPA Query Using Hibernate and Spring-boot?
提问by Benjamin Gowers
I am trying to use JPA and JPQL to query my entity and return the sum of a column (total days) from the table. I thought I had set it up right but I am getting this error:
我正在尝试使用 JPA 和 JPQL 来查询我的实体并从表中返回一列的总和（总天数）。我以为我已经设置好了，但我收到了这个错误：
Caused by: org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'myRepository':
Invocation of init method failed; nested exception is
java.lang.IllegalArgumentException: Validation failed for query for method
public abstract java.lang.Float
com.nissan.rca.repository.MyRepository.selectTotals()!
Here is a representation of my entity:
这是我的实体的表示：
@Entity
@Table(name = "TABLENAME")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class MyEntity implements Serializable {
private static final long serialVersionUID = 1L;
@EmbeddedId
private MyEntityCompositeKey myEntityCompositeKey;
@Column(name = "raiser_id")
private String raiserID;
@Column(name = "total_days")
private Float totalDays;
and here is my repository in which I make the query assigned to a method:
这是我的存储库，我在其中将查询分配给方法：
@Repository
public interface MyRepository extends JpaRepository<MyEntity, ID> {
@Query("SELECT SUM(total_days) FROM MyEntity")
Float selectTotals();
}
I call the selectTotals() method from myRepository object in my rest controller for the api mapping.
我从我的 rest 控制器中的 myRepository 对象调用 selectTotals() 方法以进行 api 映射。
@GetMapping("/getForecastTotals")
public Float getForecastTotals() {
return myRepository.selectTotals();
}
I'm unsure as to why it can't be returned as a float.
我不确定为什么它不能作为浮点数返回。
采纳答案by sedooe
It's not a valid JPQL.
它不是有效的 JPQL。
You either should have:
你应该有：
@Query("SELECT SUM(m.totalDays) FROM MyEntity m")
@Query("SELECT SUM(m.totalDays) FROM MyEntity m")
or, make it a native one:
或者，使其成为原生的：
@Query(value = "SELECT SUM(total_days) FROM MyEntity", nativeQuery = true)
@Query(value = "SELECT SUM(total_days) FROM MyEntity", nativeQuery = true)
回答by Yogendra Mishra
change your JPQL to @Query("SELECT SUM(m.totalDays) FROM MyEntity m")
将您的 JPQL 更改为 @Query("SELECT SUM(m.totalDays) FROM MyEntity m")
