JPA Criteria Queries

JPA Criteria Queries | Hibernate - Criteria Queries

for explanation watch video ::

Directory Structure:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<artifactId>JPACriteriaAPI</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>JPACriteriaAPI</name>

<url>http://maven.apache.org</url>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<maven.compiler.source>1.9</maven.compiler.source>

<maven.compiler.target>1.9</maven.compiler.target>

</properties>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<groupId>org.hibernate</groupId>

<artifactId>hibernate-core</artifactId>

<version>5.6.8.Final</version>

</dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

<scope>provided</scope>

</dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

</dependency>

</dependencies>

</project>

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD//EN"

"http://hibernate.sourceforge.net/hibernate-configuration-5.0.dtd">

<hibernate-configuration>

<session-factory>

<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/new</property>

<property name="hbm2ddl.auto">update</property>

</session-factory>

</hibernate-configuration>

Employee

package com.test.entity;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.Table;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

@Data

@AllArgsConstructor

@NoArgsConstructor

@Entity

@Table(name = "emptab")

public class Employee {

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

private Integer id;

private String name;

private String dept;

private Double sal;

public Employee(String name, Double sal,String dept) {

super();

this.name = name;

this.dept = dept;

this.sal = sal;

}

HibernateUtil

package com.test.utility;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import com.test.entity.Employee;

public class HibernateUtil {

static SessionFactory factory = null;

static {

Configuration cfg = new Configuration();

cfg.configure("hibernate.cfg.xml");

cfg.addAnnotatedClass(Employee.class);

factory = cfg.buildSessionFactory();

}

public static SessionFactory getSessionFactory() {

return factory;

}

public static Session getSession() {

return factory.openSession();

}

App

package com.test;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import com.test.entity.Employee;

import com.test.utility.HibernateUtil;

public class App

{

public static void main( String[] args )

{

//get the SessionFactory Obj

SessionFactory factory = HibernateUtil.getSessionFactory();

//get Session Obj

Session ses = HibernateUtil.getSession();

try(factory;ses){

//create the Objects

Employee e1 = new Employee("sam",5000.0,"QA");

Employee e2 = new Employee("Jhon",6000.0,"BA");

Employee e3 = new Employee("Randy",7000.0,"DEV");

Employee e4 = new Employee("Brock",5000.0,"QA");

Employee e5 = new Employee("Angela",6000.0,"BA");

Employee e6 = new Employee("Carla",7000.0,"DEV");

Employee e7 = new Employee("Raja",5000.0,"QA");

Employee e8 = new Employee("Rani",6000.0,"BA");

Employee e9 = new Employee("Ram",7000.0,"DEV");

Employee e10 = new Employee("Sandy",5000.0,"QA");

//begin the tx

ses.beginTransaction();

ses.save(e1);

ses.save(e2);

ses.save(e3);

ses.save(e4);

ses.save(e5);

ses.save(e6);

ses.save(e7);

ses.save(e8);

ses.save(e9);

ses.save(e10);

//commit the tx

ses.getTransaction().commit();

}

Test

package com.test;

import javax.persistence.Query;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaDelete;

import javax.persistence.criteria.Root;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import com.test.entity.Employee;

import com.test.utility.HibernateUtil;

public class Test {

public static void main(String[] args) {

//get the SessionFactory Obj

SessionFactory factory = HibernateUtil.getSessionFactory();

//get Session Obj

Session ses = HibernateUtil.getSession();

try(factory;ses){

/*//create cb

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Employee.class);

//create root Object

Root<Employee> root = cq.from(Employee.class);

//write the cluase conditions

cq.select(root).where(cb.and(cb.ge(root.get("id"),5),cb.le(root.get("id"),10)));

//create query object

Query query = ses.createQuery(cq);

//execute the query

List<Employee> list = query.getResultList();

//print

list.forEach(System.out::println);

//select all the emp

//create CB Obj

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Employee.class);

//create root Object

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//create query Object

Query query = ses.createQuery(cq);

//execute the query

List<Employee> list = query.getResultList();

//print the info

list.forEach(System.out::println);

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Employee.class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//clause condtion

cq.select(root).where(root.get("name").in("sam","Jhon","carla")).orderBy(cb.asc(root.get("sal")));

//create query Object

Query query = ses.createQuery(cq);

//execute the query

List<Employee> list = query.getResultList();

//print the info

list.forEach(System.out::println);

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Employee.class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//clause condition

cq.select(root).where(cb.like(root.get("name"), "s%"));

//create query Object

Query query = ses.createQuery(cq);

//execute the query

List<Employee> list = query.getResultList();

//print the info

list.forEach(System.out::println);

//select specific multiple cols

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Object[].class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//clause conditon

cq.multiselect(root.get("id"),root.get("name")).where(cb.and(cb.ge(root.get("id"),5),(cb.le(root.get("id"),10)))).orderBy(cb.desc(root.get("id")));

//create query Object

Query query = ses.createQuery(cq);

//execute the query

List<Object[]> list = query.getResultList();

//print

list.forEach(roe->{

for(Object ob : roe) {

System.out.print(ob + " ");

}

System.out.println();

});

//select ename from emp where ename like 's%'

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(String.class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//clause conditon

cq.multiselect(root.get("name")).where(cb.like(root.get("name"), "R%"));

//create query Object

Query query = ses.createQuery(cq);

//execute

List<String> list = query.getResultList();

//print

list.forEach(System.out::println);

//select count(empid) from emp

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Long.class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//clause conditon

cq.multiselect(cb.count(root.get("id")));

//create query obj

Query query = ses.createQuery(cq);

//execute

Long count = (Long)query.getSingleResult();

//print

System.out.println("Number of emps "+count);

//select count(eid),sum(sal),max(sal),min(sal),avg(sal) from emp

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CQ Object

CriteriaQuery cq = cb.createQuery(Object[].class);

//create root

Root<Employee> root = cq.from(Employee.class);//select * from Emp;

//specific col

cq.multiselect(cb.count(root.get("id")),

cb.max(root.get("sal")),

cb.min(root.get("sal")),

cb.avg(root.get("sal")),

cb.sum(root.get("sal"))

);

//create query obj

Query query = ses.createQuery(cq);

//excute

Object[] obj = (Object[])query.getSingleResult();

//print

System.out.println("Count of emo "+obj[0]);

System.out.println("max sal "+obj[1]);

System.out.println("min of sal "+obj[2]);

System.out.println("avg of sal "+obj[3]);

System.out.println("sum of sal "+obj[4]);

//update the QA dept emp sal to 8000

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create CU object

CriteriaUpdate cu = cb.createCriteriaUpdate(Employee.class);

//create root

Root<Employee> root = cu.from(Employee.class);//select * from Emp;

//clause

cu.set(root.get("sal"), 8000.0).where(cb.equal(root.get("dept"), "QA"));

//create Query Obj

Query query = ses.createQuery(cu);

//execute

ses.beginTransaction();

int count = query.executeUpdate();

//print the number of records updated

System.out.println("Number of records Updated "+count);

//commit tx

ses.getTransaction().commit();*/

//delete the emp whose name start with r

//create CB Object

CriteriaBuilder cb = ses.getCriteriaBuilder();

//create cd obj

CriteriaDelete cd = cb.createCriteriaDelete(Employee.class);

//create root

Root<Employee> root = cd.from(Employee.class);//select * from Emp;

//clause condition

cd.where(cb.like(root.get("name"), "r%"));

//create Query Object

Query query = ses.createQuery(cd);

//execute

ses.beginTransaction();

int count = query.executeUpdate();

System.out.println("Number of emp deleted "+count);

//commit the tx

ses.getTransaction().commit();

}

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