Debugging JPA Queries with H2 Database in Spring Boot

November 01, 2025

This guide shows how to debug and analyze JPA queries in Spring Boot using the H2 database and query logging.

1. Add Dependencies

In pom.xml:

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

2. Configure H2

In application.properties:

spring.datasource.url=jdbc:h2:mem:debugdb
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=create
spring.h2.console.enabled=true

3. Enable SQL Logging

Add to application.properties:

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
logging.level.org.hibernate.SQL=DEBUG
logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE

This logs SQL queries and parameter bindings.

4. Create Example Entity

@Entity
public class Employee {
  @Id @GeneratedValue
  private Long id;
  private String name;
  private String role;
}

5. Repository and Query

public interface EmployeeRepository extends JpaRepository<Employee, Long> {
    List<Employee> findByRole(String role);
}

6. Test the Query

@SpringBootTest
class EmployeeRepoTest {
  @Autowired EmployeeRepository repo;

  @Test
  void testQuery() {
    repo.save(new Employee(null, "Alice", "Dev"));
    repo.findByRole("Dev");
  }
}

Console logs will show the executed SQL and bound parameters.

7. Debug with H2 Console

Visit:

http://localhost:8080/h2-console

Use JDBC URL jdbc:h2:mem:debugdb to run queries manually and verify results.