JPA Named Queries
In this section, you will know about the JPA Named Queries and how to use in JPA application.
@NamedQueries: If you need to use more than one @NamedQuery, Then you must be use @NamedQueries annotation.
@NamedQueries({ @NamedQuery(name="allStudentRecords",query="SELECT st FROM Student st WHERE st.sroll > ?1"), @NamedQuery(name="updateStudentRecords", query="UPDATE Student st SET st.sname= ?1 WHERE st.sname= ?2") })
For developing JPA Named Queries, you need the following files:
- Database Table: student
- Model Class: Student.java
- Main Class: JPANamedQueries.java
Database Table: student
CREATE TABLE `student` ( `id` int(11) NOT NULL auto_increment, `sname` varchar(100) NOT NULL, `sroll` int(11) NOT NULL, `scourse` varchar(10) NOT NULL, PRIMARY KEY (`id`) ) |
Model Class: Student.java
/** * */ package roseindia; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.NamedQueries; import javax.persistence.NamedQuery; import javax.persistence.Table; /** * @author Administrator * */ @Entity @Table(name="student") @NamedQueries({ @NamedQuery(name="allStudentRecords",query="SELECT st FROM Student st WHERE st.sroll > ?1"), @NamedQuery(name="updateStudentRecords", query="UPDATE Student st SET st.sname= ?1 WHERE st.sname= ?2") }) public class Student { @Id @GeneratedValue private int id; /** * @return the id */ public int getId() { return id; } /** * @param id the id to set */ public void setId(int id) { this.id = id; } @Column(name="sname", length=100,nullable=false) private String sname; /** * @return the sname */ public String getSname() { return sname; } /** * @param sname the sname to set */ public void setSname(String sname) { this.sname = sname; } @Column(name="sroll",nullable=false) private int sroll; /** * @return the sroll */ public int getSroll() { return sroll; } /** * @param sroll the sroll to set */ public void setSroll(int sroll) { this.sroll = sroll; } @Column(name="scourse",length=10,nullable=false) private String scourse; /** * @return the scourse */ public String getScourse() { return scourse; } /** * @param scourse the scourse to set */ public void setScourse(String scourse) { this.scourse = scourse; } }
Main Class: JPANamedQueries.java
/** * */ package roseindia; import java.util.Iterator; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import javax.persistence.Query; /** * @author Administrator * */ public class JPANamedQueries { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub EntityManagerFactory emf=Persistence.createEntityManagerFactory("jpa"); EntityManager em=emf.createEntityManager(); try{ EntityTransaction entr=em.getTransaction(); entr.begin(); //first query Query query=em.createNamedQuery("allStudentRecords"); query.setParameter(1, 100); List stList=query.getResultList(); Iterator stIterator=stList.iterator(); while(stIterator.hasNext()){ Student st=(Student)stIterator.next(); System.out.print("sname:"+st.getSname()); System.out.print(" sroll:"+st.getSroll()); System.out.print(" scourse:"+st.getScourse()); System.out.println(); } //second query Query update_query=em.createNamedQuery("updateStudentRecords"); update_query.setParameter(1, "Suman Saurabh"); update_query.setParameter(2, "Suman"); int updateData=update_query.executeUpdate(); System.out.println(updateData +" record updated"); entr.commit(); } finally{ em.close(); } } } |
Output:
log4j:WARN No appenders could be
found for logger log4j:WARN Please initialize the log4j system properly. Hibernate: select student0_.id as id0_, student0_.scourse
as scourse0_, sname:Vinod sroll:101 scourse:MCA sname:Ravi sroll:102 scourse:M.Tech. sname:Suman sroll:103 scourse:PHD Hibernate: update student set sname=? where sname=? 1 record updated
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