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JPA Sqrt Function

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In this section, you will learn about the JPA sqrt() function. This method returns the square root of the given argument.

JPA Sqrt Function

     

In this section, you will learn about the JPA sqrt() function. This method returns the square root of the given argument.

JPA sqrtFunction:

Query query=em.createQuery("SELECT p FROM Product p WHERE SQRT(p.price) > 25");

This query retrieves all products which have the square root of price is grater than 25.

For JPA sqrt application, you need the following artifacts:

  1. Database Table: product
  2. Model Class: Product.java
  3. Main Class: JPASqrtFunction.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: JPASqrtFunction.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 JPASqrtFunction {

/**
* @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 p FROM Product p WHERE SQRT(p.price) > 25");
List pList=query.getResultList();
Iterator pIterator=pList.iterator();
while(pIterator.hasNext()){
Product pro=(Product)pIterator.next();
System.out.println("itemName:"+pro.getItemName());
}
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 product0_.id as id1_, product0_.itemName as itemName1_, product0_.price as price1_ from product product0_ where sqrt(product0_.price)>25

itemName:Mobile

itemName:T.V.

 

Product table records:

 

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Posted on: April 3, 2006

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