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Spring Data JPA - Derived Count Query

[Updated: Aug 21, 2018, Created: Aug 21, 2018]

Spring Data JPA also support count query derived methods. Instead of using 'find', we need to start our query method with 'count' keyword. For example:

public interface EmployeeRepository extends CrudRepository<Employee, Long> {
    long countByDept(String deptName);
}

Calling above method:

  long count = repo.countByDept("IT");

Example

Entity

@Entity
public class Employee {
  private @Id
  @GeneratedValue
  Long id;
  private String name;
  private String dept;
  private int salary;
    .............
}

Repository

public interface EmployeeRepository extends CrudRepository<Employee, Long> {
  long countByDept(String deptName);
  long countBySalaryGreaterThanEqual(int salary);
  long countByNameEndingWith(String endString);
  long countByNameLike(String likeString);
}

Example Client

@Component
public class ExampleClient {

  @Autowired
  private EmployeeRepository repo;

  public void run() {
      List<Employee> employees = createEmployees();
      repo.saveAll(employees);

      System.out.println(" -- finding all employees --");
      Iterable<Employee> all = repo.findAll();
      all.forEach(System.out::println);

      System.out.println(" -- finding the employee count in IT dept --");
      long count = repo.countByDept("IT");
      System.out.println(count);

      System.out.println(" -- finding the employee count with salary greater or equal to 4000  --");
      count = repo.countBySalaryGreaterThanEqual(4000);
      System.out.println(count);

      System.out.println(" -- finding the employee count with name ending with 'e'  --");
      count = repo.countByNameEndingWith("e");
      System.out.println(count);

      System.out.println(" -- finding the employee count with name like '%a_a' --");
      count = repo.countByNameLike("%a_a");
      System.out.println(count);
  }

  private List<Employee> createEmployees() {
      return Arrays.asList(
              Employee.create("Diana", "Admin", 3000),
              Employee.create("Mike", "IT", 1000),
              Employee.create("Rose", "IT", 4000),
              Employee.create("Sara", "Admin", 3500),
              Employee.create("Tanaka", "IT", 3000),
              Employee.create("Charlie", "IT", 4500)
      );
  }
}

Main class

public class ExampleMain {

  public static void main(String[] args) {
      AnnotationConfigApplicationContext context =
              new AnnotationConfigApplicationContext(AppConfig.class);
      ExampleClient exampleClient = context.getBean(ExampleClient.class);
      exampleClient.run();
      EntityManagerFactory emf = context.getBean(EntityManagerFactory.class);
      emf.close();
  }
}
 -- finding all employees --
Employee{id=1, name='Diana', dept='Admin', salary=3000}
Employee{id=2, name='Mike', dept='IT', salary=1000}
Employee{id=3, name='Rose', dept='IT', salary=4000}
Employee{id=4, name='Sara', dept='Admin', salary=3500}
Employee{id=5, name='Tanaka', dept='IT', salary=3000}
Employee{id=6, name='Charlie', dept='IT', salary=4500}
-- finding the employee count in IT dept --
4
-- finding the employee count with salary greater or equal to 4000 --
2
-- finding the employee count with name ending with 'e' --
3
-- finding the employee count with name like '%a_a' --
3

Example Project

Dependencies and Technologies Used:

  • spring-data-jpa 2.0.9.RELEASE: Spring Data module for JPA repositories.
    Uses org.springframework:spring-context version 5.0.8.RELEASE
  • hibernate-core 5.3.5.Final: Hibernate's core ORM functionality.
    Implements javax.persistence:javax.persistence-api version 2.2
  • h2 1.4.197: H2 Database Engine.
  • JDK 1.8
  • Maven 3.5.4

Derived Count Query Methods Example Select All Download
  • spring-data-jpa-derived-count-query
    • src
      • main
        • java
          • com
            • logicbig
              • example
                • EmployeeRepository.java
          • resources
            • META-INF

    See Also