Handling Transactions in H2 Database with Spring Boot

October 18, 2025

This guide shows how to handle transactions in Spring Boot using the H2 database to ensure consistent data operations.

1. Add Dependencies

In pom.xml:

<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

2. Configure H2 Database

In application.properties:

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=update

3. Create Entity

import jakarta.persistence.*;

@Entity
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String owner;
    private Double balance;
}

4. Repository

import org.springframework.data.jpa.repository.JpaRepository;

public interface AccountRepository extends JpaRepository<Account, Long> {
}

5. Service with Transactions

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
public class AccountService {

    private final AccountRepository repo;

    public AccountService(AccountRepository repo) {
        this.repo = repo;
    }

    @Transactional
    public void transfer(Long fromId, Long toId, Double amount) {
        Account from = repo.findById(fromId).orElseThrow();
        Account to = repo.findById(toId).orElseThrow();

        from.setBalance(from.getBalance() - amount);
        to.setBalance(to.getBalance() + amount);

        repo.save(from);
        repo.save(to);
    }
}

Here, @Transactional ensures both updates happen together, or none at all.

6. Test Transaction Rollback

If an exception occurs inside transfer(), the transaction will rollback and balances stay unchanged.