The @Query annotation can also be used to declare native queries. For that we need to set the @Query#nativeQuery flag to true.
Example
Entity
@Entity
public class Employee {
private @Id
@GeneratedValue
Long id;
private String name;
private String dept;
private int salary;
.............
}
The repository
package com.logicbig.example;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import java.util.List;
public interface EmployeeRepository extends CrudRepository<Employee, Long> {
@Query(value = "SELECT max(avg_sal), min(avg_sal) FROM (SELECT dept , avg(salary) as avg_sal "
+ "from Employee GROUP BY dept HAVING dept in ?1) ", nativeQuery = true)
public Object[][] findMaxMinAvgSalariesOfDept(List<String> deptNames);
}
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 max/min of average salaries in Admin and IT depts --");
Object[][] maxAvgSalaries = repo.findMaxMinAvgSalariesOfDept(Arrays.asList("Admin", "IT"));
for (Object[] maxAvgSalary : maxAvgSalaries) {
System.out.println("max avg salary: " + maxAvgSalary[0]);
System.out.println("min avg salary: " + maxAvgSalary[0]);
}
}
private List<Employee> createEmployees() {
return Arrays.asList(
Employee.create("Diana", "Admin", 2000),
Employee.create("Mike", "Sale", 1000),
Employee.create("Rose", "IT", 4000),
Employee.create("Sara", "Admin", 3500),
Employee.create("Randy", "Sale", 3000),
Employee.create("Charlie", "IT", 2500)
);
}
}
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=2000} Employee{id=2, name='Mike', dept='Sale', salary=1000} Employee{id=3, name='Rose', dept='IT', salary=4000} Employee{id=4, name='Sara', dept='Admin', salary=3500} Employee{id=5, name='Randy', dept='Sale', salary=3000} Employee{id=6, name='Charlie', dept='IT', salary=2500} -- finding max/min of average salaries in Admin and IT depts -- max avg salary: 3250 min avg salary: 3250
Example ProjectDependencies and Technologies Used: - spring-data-jpa 2.0.7.RELEASE: Spring Data module for JPA repositories.
Uses org.springframework:spring-context version 5.0.6.RELEASE - hibernate-core 5.3.1.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 3.3.9
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