Here’s an example of building a sample Spring Data JPA application with H2 database and a one-to-many relationship between two entities:
In your project’s pom.xml file, include the necessary dependencies for Spring Data JPA, H2 database, and Spring Web:
<dependencies>
    <!-- Spring Data JPA -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <!-- H2 Database -->
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!-- Spring Boot Starter -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>
In your application.properties file, provide the necessary configurations for the H2 database:
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=
spring.h2.console.enabled=true
spring.jpa.hibernate.ddl-auto=create