In this tutorial, we're gonna build a Spring Boot + PostgreSQL example with Maven that uses Spring Data JPA/Hibernate to interact with PostgreSQL database and export Rest CRUD API. You'll know:

• How to configure Spring Data, JPA, Hibernate to work with PostgreSQL Database
• How to define Data Models and Repository interfaces
• Way to create Spring Rest Controller to process HTTP requests
• Way to use Spring Data JPA to interact with PostgreSQL Database

Full Article: Spring Boot + PostgreSQL + Maven: CRUD example

Overview of Spring Boot, PostgreSQL example with Maven

We will build a Spring Boot + PostgreSQL + Rest CRUD API for a Tutorial application in that:

• Each Tutotial has id, title, description, published status.
• Apis help to create, retrieve, update, delete Tutorials.
• Apis also support custom finder methods such as find by published status or by title.

These are APIs that we need to provide:

• We make CRUD operations & finder methods with Spring Data JPA's JpaRepository.
• The database will be PostgreSQL by configuring project dependency & datasource.

Technology

• Java 17 / 11 / 8
• Spring Boot 3 / 2 (with Spring Web MVC, Spring Data JPA)
• PostgreSQL
• Maven

Maven Project Structure

Let me explain it briefly.

– Tutorial data model class corresponds to entity and table tutorials.
– TutorialRepository is an interface that extends JpaRepository for CRUD methods and custom finder methods. It will be autowired in TutorialController.
– TutorialController is a RestController which has request mapping methods for RESTful requests such as: getAllTutorials, createTutorial, updateTutorial, deleteTutorial, findByPublished...
– Configuration for Spring Datasource, JPA & Hibernate in application.properties.
– pom.xml contains dependencies for Spring Boot and PostgreSQL.

Run the Application

Run Spring Boot + PostgreSQL application with Maven: mvn spring-boot:run.

tutorials table will be automatically generated in Database.
If you check PostgreSQL for example, you can see things like this:

testdb=# \d tutorials
             Table "public.tutorials"
   Column    |          Type          | Modifiers
-------------+------------------------+-----------
 id          | bigint                 | not null
 description | character varying(255) |
 published   | boolean                |
 title       | character varying(255) |
Indexes:
    "tutorials_pkey" PRIMARY KEY, btree (id)

Create some Tutorials:

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  1 | Tut#1 Description | f         | Spring Boot Tut#1
  2 | Tut#2 Description | f         | PostgreSQL Tut#2
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  4 | Tut#4 Description | f         | Maven Tut#4
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
(5 rows)

Update some Tutorials:

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
  2 | Desc for Tut#2    | t         | PostgreSQL DB Tut#2
  4 | Desc for Tut#4    | t         | Maven Tut#4
  1 | Desc for Tut#1    | t         | Spring Boot Tut#1
(5 rows)

Retrieve all Tutorials:

Get a Tutorial by Id:

Find all published Tutorials:

Find all Tutorials which title contains 'ring':

Delete a Tutorial:

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
  2 | Desc for Tut#2    | t         | PostgreSQL DB Tut#2
  1 | Desc for Tut#1    | t         | Spring Boot Tut#1
(4 rows)

Delete all Tutorials:

testdb=# SELECT * FROM tutorials;
 id | description | published | title
----+-------------+-----------+-------
(0 rows)

Source code

For step by step instruction and Github, please visit:
Full Article: Spring Boot + PostgreSQL + Maven: CRUD example

Further Reading

Spring Boot One To Many example with Spring JPA, Hibernate

If you want to add Pagination to this Spring project, you can find the instruction at:
Spring Boot Pagination & Filter example | Spring JPA, Pageable

To sort/order by multiple fields:
Spring Data JPA Sort/Order by multiple Columns | Spring Boot

Handle Exception for this Rest APIs is necessary:

• Spring Boot @ControllerAdvice & @ExceptionHandler example
• @RestControllerAdvice example in Spring Boot

Or way to write Unit Test for the JPA Repository:
Spring Boot Unit Test for JPA Repositiory with @DataJpaTest

Security:
Spring Boot, Spring Security, PostgreSQL: JWT Authentication example

You can also know:

• how to deploy this Spring Boot App on AWS (for free) with this tutorial.
• way to upload an Excel file and store the data in MySQL database with this post
• upload CSV file and store the data in MySQL with this post.

Fullstack examples:

• Vue.js + Spring Boot + PostgreSQL example
• Angular 8 + Spring Boot + PostgreSQL example
• Angular 10 + Spring Boot + PostgreSQL example
• Angular 11 + Spring Boot + PostgreSQL example
• React + Spring Boot + PostgreSQL example