Spring Data JPA CrudRepository - delete() Method

In this tutorial, we will learn how to use the Spring Data - CrudRepository interface provided the delete() method with an example. 

As the name depicts, the delete() method allows us to delete an entity from the database table. It belongs to the CrudRepository interface defined by Spring Data.

Maven Dependencies

<?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>2.6.1</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>net.javaguides</groupId>
	<artifactId>spring-data-jpa-course</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>spring-data-jpa-course</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>11</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</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>
			</plugin>
		</plugins>
	</build>

</project>

Product Entity

Let's first create a Product entity that we are going to use to save and delete to/from the database:

package net.javaguides.springdatajpacourse.entity;

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

import javax.persistence.*;
import java.math.BigDecimal;
import java.util.Date;

@Entity
@Table(name="products")
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "sku")
    private String sku;

    @Column(name = "name")
    private String name;

    @Column(name = "description")
    private String description;

    @Column(name = "price")
    private BigDecimal price;

    @Column(name = "image_url")
    private String imageUrl;

    @Column(name = "active")
    private boolean active;

    @Column(name = "date_created")
    @CreationTimestamp
    private Date dateCreated;

    @Column(name = "last_updated")
    @UpdateTimestamp
    private Date lastUpdated;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getSku() {
        return sku;
    }

    public void setSku(String sku) {
        this.sku = sku;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public BigDecimal getPrice() {
        return price;
    }

    public void setPrice(BigDecimal price) {
        this.price = price;
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Date getLastUpdated() {
        return lastUpdated;
    }

    public void setLastUpdated(Date lastUpdated) {
        this.lastUpdated = lastUpdated;
    }

    @Override
    public String toString() {
        return "Product{" +
                "id=" + id +
                ", sku='" + sku + '\'' +
                ", name='" + name + '\'' +
                ", description='" + description + '\'' +
                ", price=" + price +
                ", imageUrl='" + imageUrl + '\'' +
                ", active=" + active +
                ", dateCreated=" + dateCreated +
                ", lastUpdated=" + lastUpdated +
                '}';
    }
}

ProductRepository

Let's create ProductRepository which extends the CrudRepository interface. As we know that CrudRepository interface provides the delete() method so our ProductRepository interface should extend to the CrudRepository interface to get all its methods:

import net.javaguides.springdatajpacourse.entity.Product;
import org.springframework.data.repository.CrudRepository;

public interface ProductRepository extends CrudRepository<Product, Long> {

}

Configure MySQL and Hibernate Properties

Let's use the MySQL database to store and retrieve the data in this example and we gonna use Hibernate properties to create and drop tables.

Open the application.properties file and add the following configuration to it:

spring.datasource.url=jdbc:mysql://localhost:3306/ecommerce?useSSL=false
spring.datasource.username=root
spring.datasource.password=Mysql@123

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect

spring.jpa.hibernate.ddl-auto = create-drop

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
Make sure that you will create ecommerce database before running the Spring boot application.
Also, change the MySQL username and password as per your MySQL installation on your machine.

Testing delete() Method

In order to test the delete() method, we gonna use CommandLineRunner.run() method to execute the testing code while Spring boot application startup: 
import net.javaguides.springdatajpacourse.entity.Product;
import net.javaguides.springdatajpacourse.repository.ProductRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.math.BigDecimal;
import java.util.Date;

@SpringBootApplication
public class SpringDataJpaCourseApplication implements CommandLineRunner{

	public static void main(String[] args) throws Exception {
		SpringApplication.run(SpringDataJpaCourseApplication.class, args);
	}

	@Autowired
	private ProductRepository productRepository;

	@Override
	public void run(String... args) throws Exception {
		Product product = new Product();
        product.setName("product 1");
        product.setDescription("product 1 desc");
        product.setPrice(new BigDecimal(100));
        product.setDateCreated(new Date());
        product.setLastUpdated(new Date());
        product.setSku("product 1 sku");
        product.setActive(true);
        product.setImageUrl("product1.png");
        productRepository.save(product);

        // DELETE PRODUCT
        productRepository.delete(product);
	}
}

After finishing the Spring boot application, you can able to see Hibernate-generated SQL statements in a console. Note that delete() method first get an entity by id from that database table and delete using entity id (primary key) hence you can see select SQL statement in a console.
Hibernate: 
    insert 
    into
        products
        (active, date_created, description, image_url, last_updated, name, price, sku) 
    values
        (?, ?, ?, ?, ?, ?, ?, ?)
Hibernate: 
    select
        product0_.id as id1_0_0_,
        product0_.active as active2_0_0_,
        product0_.date_created as date_cre3_0_0_,
        product0_.description as descript4_0_0_,
        product0_.image_url as image_ur5_0_0_,
        product0_.last_updated as last_upd6_0_0_,
        product0_.name as name7_0_0_,
        product0_.price as price8_0_0_,
        product0_.sku as sku9_0_0_ 
    from
        products product0_ 
    where
        product0_.id=?
Hibernate: 
    delete 
    from
        products 
    where
        id=?
INSERT SQL statements to save an entity:
    insert 
    into
        products
        (active, date_created, description, image_url, last_updated, name, price, sku) 
    values
        (?, ?, ?, ?, ?, ?, ?, ?)
DELETE SQL statement to delete an entity by id:
    delete 
    from
        products 
    where
        id=?

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