用hibernate @NamedNativeQuery返回一个数值 [英] Returning a numeric value with hibernate @NamedNativeQuery

问题描述

我有这个问题：

...如果查询只是返回一个数字（即，查询就像'select count（id）where ...）我反对这个错误

$ b org.hibernate.cfg.NotYetImplementedException：纯原生标量查询尚未支持

欲了解更多详情，请参阅： http://atechnicaljourney.wordpress.com/2012/09/30/hibernate-pure-native-scalar-queries-are-not-yet-supported/

我不想拥有一个包装类，特别是不需要额外的表。这样做的正确方法是什么？

解决方案

面对纯原生标量查询尚未支持。我需要运行计数查询的查询名称作为参数，其中一个查询必须是原生SQL。
能够通过创建假实体来克服：

  import javax.persistence.Column; 
 import javax.persistence.Entity; 
 import javax.persistence.Id; 
 
 / ** 
 *简单的包装实体可以解决有限的hibernate纯原生查询
 *支持。在HQL查询不可能的情况下
 * / 
 @SuppressWarnings（serial）
 @Entity 
 public class CountDTO extends Number {
 
 @Id 
 @Column（name =COUNT）
私有长计数; 
 
 @Override 
 public double doubleValue（）{
 return count.doubleValue（）; 
 
 
 @Override 
 public float floatValue（）{
 return count.floatValue（）; 
} 
 
 @Override 
 public int intValue（）{
 return count.intValue（）; 
 
 
 @Override 
 public long longValue（）{
 return count.longValue（）; 
} 
 
} 
  

然后我将 resultClass = CountDTO.class

  @NamedNativeQueries（{
 @NamedNativeQuery =postIdSecurity，
 query =select count（...）...，resultClass = CountDTO.class）
}）
  

$ b $

并获得计数：

 （（Number）getEntityManager（） .createNamedQuery（qryName）。
 setParameter（...）。getSingleResult（））。longValue（）
  

积分转到： http：// jdevelopment。 nl / hibernates-pure-native-scalar-queries-supported /＃comment-1533

I've this question:

"... if the query just returns a number (i.e., the query is something like ‘select count(id) where…..) I came up against this error

org.hibernate.cfg.NotYetImplementedException: Pure native scalar queries are not yet supported"

For more details see: http://atechnicaljourney.wordpress.com/2012/09/30/hibernate-pure-native-scalar-queries-are-not-yet-supported/

I don't want to have a wrapper class and especially not some extra table. What is the proper way of doing this?

解决方案

Faced "Pure native scalar queries are not yet supported". I need to run count queries having a name of the query as parameter and one of the queries must be native SQL. Was able to overcome by creating fake entity:

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

/**
 * Simple wrapper entity work around for the limited hibernate pure native query
 * support. Where an HQL query is not possible
 */
@SuppressWarnings("serial")
@Entity
public class CountDTO  extends Number {

    @Id
    @Column(name = "COUNT")
    private Long count;

    @Override
    public double doubleValue() {
        return count.doubleValue();
    }

    @Override
    public float floatValue() {
        return count.floatValue();
    }

    @Override
    public int intValue() {
        return count.intValue();
    }

    @Override
    public long longValue() {
        return count.longValue();
    }

}

Then I set resultClass = CountDTO.class

@NamedNativeQueries({
    @NamedNativeQuery (name="postIdSecurity",
            query="select count(...) ...", resultClass = CountDTO.class)
})

And get count:

    ((Number) getEntityManager().createNamedQuery(qryName).
setParameter(...).getSingleResult()).longValue()

Credits go to: http://jdevelopment.nl/hibernates-pure-native-scalar-queries-supported/#comment-1533

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