JPA Sum Function
In this section, you will learn about sum
function of aggregate function of JPQL (Java Persistence Query Language).
The sum function to calculate the sum of given fields. Following example
displays you how to use the sum function in your jpa application.
JPA Sum Function:
| Query query=em.createQuery("SELECT
SUM(p.price) FROM Product p"); |
This query calculate the sum of total price of product.
Developing this application, you need the following
files:
- Database Table: product
- Model Class: Product.java
- Main Class: JPASumFunctoion.java
Database Table: product
CREATE TABLE `product` (
`id` int(11) NOT NULL auto_increment,
`itemName` varchar(50) NOT NULL,
`price` double NOT NULL,
PRIMARY KEY (`id`)
) |
Model Class: Product.java
/**
*
*/
package roseindia;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
/**
* @author Administrator
*
*/
@Entity
@Table(name="product")
public class Product {
@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="itemName",length=50,nullable=false)
private String itemName;
/**
* @return the itemName
*/
public String getItemName() {
return itemName;
}
/**
* @param itemName the itemName to set
*/
public void setItemName(String itemName) {
this.itemName = itemName;
}
@Column(name="price")
private double price;
/**
* @return the price
*/
public double getPrice() {
return price;
}
/**
* @param price the price to set
*/
public void setPrice(double price) {
this.price = price;
}
}
|
Main Class: JPASumFunctoion.java
/**
*
*/
package roseindia;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
/**
* @author Administrator
*
*/
public class JPASumFunctoion {
/**
* @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 SUM(p.price) FROM Product p");
Number sumOfPrice=(Number) query.getSingleResult();
System.out.println("SUM result:"+sumOfPrice);
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 SUM(product0_.price) as col_0_0_ from
product product0_
SUM result:14850.0
|
|
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