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JPA Positional Parameter

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In this section, you will learn about the JPA Positional Parameter and how to use in your JPA application

JPA Positional Parameter

     

In this section, you will learn about the JPA Positional Parameter and how to use in your JPA application. JPA Queries are convenient to pass the value in parameter. So, We don't have use the same query for different values. To use parameter to add prefix by "?" (question mark) after that staring number. Positional parameter numbered are staring from "1". Positional parameter is using with query.setParameter() method.

Numbered Parameters:

Query query = em.createQuery(
"SELECT st FROM Student st WHERE st.sroll= ?1 AND st.scourse= ?2");
query.setParameter(1, 100);
query.setParameter(2, "MCA");

For developing JPA Named Parameter, you need the following artifacts:

  1. Database Table: student
  2. Model Class: Student.java
  3. Main Class: JPAPositionalParameter.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")

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: JPAPositionalParameter.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 JPAPositionalParameter {

/**
* @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();
Query query = em.createQuery("SELECT st FROM Student st WHERE st.sroll= ?1 AND st.scourse= ?2");
query.setParameter(1, 101);
query.setParameter(2, "MCA");
List stList=query.getResultList();
Iterator stIterator=stList.iterator();
while(stIterator.hasNext()){
Student st=(Student)stIterator.next();
System.out.print("id:"+st.getId());
System.out.print(" sname:"+st.getSname());
System.out.print(" sroll:"+st.getSroll());
System.out.print(" scourse:"+st.getScourse());
System.out.println();
}
entr.commit();
}
finally{
em.close();
}
}
}

Output:

log4j:WARN No appenders could be found for logger
(org.hibernate.cfg.annotations.Version).

log4j:WARN Please initialize the log4j system properly.

Hibernate: select student0_.id as id0_, student0_.scourse as
scourse0_, student0_.sname as sname0_, student0_.sroll as
sroll0_ from student student0_ where student0_.sroll=?
and student0_.scourse=?

id:1 sname:Vinod sroll:101 scourse:MCA

 

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Posted on: September 29, 2006

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