For instruction, please visit:
Spring Boot PostgreSQL with Maven example using Spring Data JPA
More practice:
Spring Boot Pagination & Filter example | Spring JPA, Pageable
Spring Data JPA Sort/Order by multiple Columns | Spring Boot
Security:
Spring Boot, Spring Security, PostgreSQL: JWT Authentication & Authorization example
Fullstack:
Run both Back-end & Front-end in one place:
mvn spring-boot:run