March 1st, 2023
JPQL Queries
				
					<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.0.2</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.brains.jpa.hibernate</groupId>
	<artifactId>jpa-hibernate-demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>jpa-hibernate-demo</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>17</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<excludes>
						<exclude>
							<groupId>org.projectlombok</groupId>
							<artifactId>lombok</artifactId>
						</exclude>
					</excludes>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

				
			
				
					spring.datasource.url=jdbc:h2:mem:testdb;NON_KEYWORDS=USER;DB_CLOSE_ON_EXIT=FALSE
spring.h2.console.enabled=true
spring.jpa.defer-datasource-initialization=true

# Turn Statistics ON
#spring.jpa.properties.hibernate.generate_statistics=true
logging.level.org.hibernate.stat=debug
#logging.level.root=trace
# Show all queries
spring.jpa.show-sql=true

# Format the queries
spring.jpa.properties.hibernate.format_sql=true
				
			
				
					package com.brains.jpa.hibernate.jpahibernatedemo.entity;

import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;

import org.hibernate.annotations.CreationTimestamp;
import org.hibernate.annotations.UpdateTimestamp;

import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;
import jakarta.persistence.ManyToMany;
import jakarta.persistence.OneToMany;
import lombok.AccessLevel;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.Setter;

@Entity
@Data
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Course {
	
	@Id
	@GeneratedValue
	private Long id;
	
	@NonNull
	private String name;
	
	@Setter(AccessLevel.NONE)
	@OneToMany(mappedBy = "course", fetch = FetchType.LAZY)
	private List<Review> reviews = new ArrayList<>();
	
	@ManyToMany(mappedBy = "courses")
	@Setter(value = AccessLevel.NONE)
	private List<Student> students = new ArrayList<>();
	
	public void addStudent(Student student) {
		this.students.add(student);
	}
	
	public void addReview(Review review) {
		this.reviews.add(review);
	}
	
	public void removeReview(Review review) {
		this.reviews.remove(review);
	}
	
	@UpdateTimestamp
	private LocalDateTime lastUpdatedDate;

	@CreationTimestamp
	private LocalDateTime createdDate;
	
	public Course(String name) {
		this.name = name;
	}
}

				
			
				
					package com.brains.jpa.hibernate.jpahibernatedemo.entity;

import java.util.ArrayList;
import java.util.List;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.JoinTable;
import jakarta.persistence.ManyToMany;
import jakarta.persistence.OneToOne;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.Setter;
import lombok.ToString;

@Entity
@Data @NoArgsConstructor(access = AccessLevel.PROTECTED)
@AllArgsConstructor
@RequiredArgsConstructor
public class Student {

	@Id
	@GeneratedValue
	private Long id;
	
	@NonNull
	@Column(nullable = false)
	private String name;
	
	@OneToOne(fetch = FetchType.LAZY)
	private Passport passport;
	
	@ToString.Exclude
	@ManyToMany
	@Setter(value = AccessLevel.NONE)
	@JoinTable(name = "STUDENT_COURSE", 
			joinColumns = @JoinColumn(name = "STUDENT_ID"),
			inverseJoinColumns = @JoinColumn(name = "COURSE_ID")
			)
	private List<Course> courses = new ArrayList<>();
	
	public void addCourse(Course course) {
		this.courses.add(course);
	}
}
				
			
				
					package com.brains.jpa.hibernate.jpahibernatedemo.entity;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;
import jakarta.persistence.OneToOne;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.ToString;

@Entity
@Data @NoArgsConstructor(access = AccessLevel.PROTECTED)
@AllArgsConstructor
@RequiredArgsConstructor
public class Passport {

	@Id
	@GeneratedValue
	private Long id;
	
	@NonNull
	@Column(nullable = false)
	private String number;
	
	@ToString.Exclude
	@OneToOne(fetch = FetchType.LAZY, mappedBy = "passport")
	private Student student;
}
				
			
				
					package com.brains.jpa.hibernate.jpahibernatedemo.entity;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;
import jakarta.persistence.ManyToOne;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.ToString;

@Entity
@Data @NoArgsConstructor(access = AccessLevel.PROTECTED)
@AllArgsConstructor
@RequiredArgsConstructor
public class Review {

	@Id
	@GeneratedValue
	private Long id;
	
	@NonNull
	private String rating;
	
	@NonNull
	private String description;
	
	@ToString.Exclude
	@ManyToOne
	private Course course;
}

				
			
				
					insert into course(id, name, created_date, last_updated_date) 
values(10001, 'JPA in 5 steps', LOCALTIMESTAMP, LOCALTIMESTAMP);
insert into course(id, name, created_date, last_updated_date) 
values(10002, 'JDBC in 10 steps', LOCALTIMESTAMP, LOCALTIMESTAMP);
insert into course(id, name, created_date, last_updated_date) 
values(10003, 'JPQL in 50 steps', LOCALTIMESTAMP, LOCALTIMESTAMP);

insert into passport(id, number)
values(40001,'E12345');
insert into passport(id, number)
values(40002,'F212345');
insert into passport(id, number)
values(40003,'GE23451');

insert into student(id, name, passport_id)
values(20001,'Ranga',40001);
insert into student(id, name, passport_id)
values(20002,'Adam',40002);
insert into student(id, name, passport_id)
values(20003,'Jane',40003);

insert into review(id, rating, description, course_id)
values(50001,'1', 'Great course', 10001);
insert into review(id, rating, description, course_id)
values(50002,'3', 'Nice course', 10001);
insert into review(id, rating, description, course_id)
values(50004,'5', 'Good you are writing', 10003);

insert into student_course(student_id, course_id)
values(20001, 10001);
insert into student_course(student_id, course_id)
values(20002, 10001);
insert into student_course(student_id, course_id)
values(20003, 10001);
insert into student_course(student_id, course_id)
values(20001, 10003);



				
			
				
					package com.brains.jpa.hibernate.jpahibernatedemo;

import static org.junit.jupiter.api.Assertions.*;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.brains.jpa.hibernate.jpahibernatedemo.entity.Course;
import com.brains.jpa.hibernate.jpahibernatedemo.entity.Student;

import jakarta.persistence.EntityManager;
import jakarta.persistence.TypedQuery;
import jakarta.transaction.Transactional;

@SpringBootTest(classes = JpaHibernateDemoApplication.class)
class JPQLQueryTest {

	private Logger logger = LoggerFactory.getLogger(getClass());
	
	@Autowired
	EntityManager em;
	
	// get course which do not have any student
//	@Test
	@Transactional
	void jpql_courses_without_students() {
		TypedQuery<Course> createQuery = em.createQuery("select c from Course c where c.students is empty", Course.class);
		List<Course> resultList = createQuery.getResultList();
		logger.info("Courses: -> {}", resultList);
	}
	
	// get courses where which has more thatn 2 students
//	@Test
	@Transactional
	void jpql_courses_with_atleast_2_students() {
		TypedQuery<Course> createQuery = em.createQuery("select c from Course c where size(c.students) > 2", Course.class);
		List<Course> resultList = createQuery.getResultList();
		logger.info("Courses: -> {}", resultList);
	}
	
	// get courses order by student size
	// by default, order by is ascending(0-10)
//	@Test
	@Transactional
	void jpql_courses_ordered_by_students() {
		TypedQuery<Course> createQuery = em.createQuery("select c from Course c order by size(c.students) desc", Course.class);
		List<Course> resultList = createQuery.getResultList();
		logger.info("Courses: -> {}", resultList);
	}
	
	// get students whose passport number contains 12345
	/**
	 * Other functions
	 * ===============
	 * like
	 * Between 100 and 500
	 * Is Null
	 * 
	 * ---- On String ------
	 * upper, lower, trim, length
	 */
	@Test
	@Transactional
	void jpql_sudent_passport_matching() {
		TypedQuery<Student> createQuery = em.createQuery("select s from Student s where s.passport.number like '%1234%'", Student.class);
		List<Student> resultList = createQuery.getResultList();
		logger.info("Courses: -> {}", resultList);
	}

}

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