Named Native Query

DrRakha

Using named native query , you can write simple SQL queries and run it on your JPA model . You may need to do this in cases when you need a specific database query that you can't do with EJB-QL . Sometimes for performance issues .

You can add native query using @NamedNativeQuery annotation .

Code:

package com.codemiles.jpa;
import java.util.Collection;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.NamedNativeQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;



@Entity
@Table(name="TOPIC")
@NamedNativeQuery(name = "nativeTopicByDate", query = "SELECT topic.TITLE, topic.CREATION_DATE FROM TOPIC topic " +
        "WHERE topic.MODIFED_DATE=?", resultClass = Topic.class)
    

public class Topic implements java.io.Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Id
    private int Id;
    private String title;
    private Date creationDate;
    private Date modifedDate;
    private String content;
    @OneToMany(mappedBy="topic")
    private Collection<Comment> comments;

    public int getId() {
        return Id;
    }
    public void setId(int id) {
        Id = id;
    }
    
    @Column(name="TITLE")
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    
    @Column(name="CREATION_DATE")
    public Date getCreationDate() {
        return creationDate;
    }
    public void setCreationDate(Date creationDate) {
        this.creationDate = creationDate;
    }
    
    @Column(name="MODIFED_DATE")
    public Date getModifedDate() {
        return modifedDate;
    }
    public void setModifedDate(Date modifedDate) {
        this.modifedDate = modifedDate;
    }
    
    @Column(name="CONTENT")
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public void setComments(Collection<Comment> comments) {
    this.comments = comments;
    }
    public Collection<Comment> getComments() {
    return comments;
    }
}
 

Code:

package com.codemiles.jpa;

import java.util.Date;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

/**
 * @author codemiles.
 *
 */
public abstract class JPAService {
    private EntityManager entityManager;

    /**
     * @param args
     */
    public void insertTopic(Topic topic) {
    EntityManagerFactory factory = Persistence
            .createEntityManagerFactory("persistenceUnitName");
    entityManager = factory.createEntityManager();
    entityManager.getTransaction().begin();
     Date date = new Date(System.currentTimeMillis());
    List<Topic> list = loadTopicByDate( date);
    if (list != null) {
        for (Topic currentTopic : list) {
        System.out.println("Topic id#(" + currentTopic.getId()
                + " ). Title = " + currentTopic.getTitle()
                + " , Content = " + currentTopic.getContent());
        }
    }
    entityManager.persist(topic);
    entityManager.getTransaction().commit();
    entityManager.close();
    factory.close();

    }

 
 
    /**
     * Using native query .
     * @param date
     *   date of the creation .
     * @return
     *  List of topics retrieved 
     */
    public  List<Topic> loadTopicByDate(Date date) {
    Query query = entityManager.createNativeQuery("nativeTopicByDate");
    query.setParameter(1, date);
 
    List<Topic> topicList = query.getResultList();
    return topicList;
    }

}

 

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