Spring Data Jpa: @Query: Perform JPA and native queries

@Query annotation is used to perform both JPA and native queries.

For the below entity

@Entity

@Table(name = "my_employee")

public class Employee {

         @Id

         @GeneratedValue(strategy = GenerationType.AUTO)

         @Column(name = "employee_id")

         private int id;

         .....

         .....

}

Example 1: JPA Query

@Query("SELECT e.firstName FROM Employee e")

List<String> getFirstNames();

As you see, we are using Entity class name ‘Employee’ to execute JPA query.

Example 2: Native Query

@Query(value = "SELECT e.first_name FROM my_employee e", nativeQuery=true)

List<String> getFirstNamesNativeQuery();

You should use actual table name ‘my_employee’ and column name ‘first_name’ while executing native query. You should set nativeQuery to true, while executing native query.

Find the below working application.

Step 1: Create 'com.sample.app.model' and define Employee.java like below.

Employee.java

package com.sample.app.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "my_employee")
public class Employee {
 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 @Column(name = "employee_id")
 private int id;

 @Column(name = "first_name")
 private String firstName;

 @Column(name = "last_name")
 private String lastName;

 @Column(name = "age")
 private int age;

 @Column(name = "salary")
 private double salary;

 public int getId() {
  return id;
 }

 public void setId(int id) {
  this.id = id;
 }

 public String getFirstName() {
  return firstName;
 }

 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 public String getLastName() {
  return lastName;
 }

 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

 public int getAge() {
  return age;
 }

 public void setAge(int age) {
  this.age = age;
 }

 public double getSalary() {
  return salary;
 }

 public void setSalary(double salary) {
  this.salary = salary;
 }

 public static EmployeeBuilder builder() {
  return new EmployeeBuilder();
 }

 public static class EmployeeBuilder {
  private Employee emp;

  public EmployeeBuilder() {
   emp = new Employee();
  }

  public EmployeeBuilder firstName(String firstName) {
   emp.setFirstName(firstName);
   return this;
  }

  public EmployeeBuilder lastName(String lastName) {
   emp.setLastName(lastName);
   return this;
  }
  
  public EmployeeBuilder age(int age) {
   emp.setAge(age);
   return this;
  }
  
  public EmployeeBuilder salary(double salary) {
   emp.setSalary(salary);
   return this;
  }

  public Employee build() {
   return emp;
  }
 }

 @Override
 public String toString() {
  StringBuilder builder = new StringBuilder();
  builder.append("Employee [id=").append(id).append(", firstName=").append(firstName).append(", lastName=")
    .append(lastName).append(", age=").append(age).append(", salary=").append(salary).append("]");
  return builder.toString();
 }

}

Step 2: Create a package 'com.sample.app.repository' and define EmployeeRepository interface like below.

EmployeeRepository.java

package com.sample.app.repository;

import java.util.List;

import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;

import com.sample.app.model.Employee;

public interface EmployeeRepository extends CrudRepository<Employee, Integer> {

 @Query("SELECT e.firstName FROM Employee e")
 List<String> getFirstNames();
 
 @Query(value = "SELECT e.first_name FROM my_employee e", nativeQuery=true)
 List<String> getFirstNamesNativeQuery();
}

Step 3: Create application.properties file under 'src/main/resources' folder.

application.properties

logging.level.root=WARN
logging.level.org.hibernate=ERROR

## H2 specific properties
spring.h2.console.enabled=true
spring.h2.console.path=/h2

spring.datasource.url=jdbc:h2:file:~/db/myOrg.db;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1;

spring.datasource.username=krishna
spring.datasource.password=password123

spring.datasource.driverClassName=org.h2.Driver

## JPA specific properties
# Creates the schema, destroying previous data.
spring.jpa.hibernate.ddl-auto=create

spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

#spring.jpa.show-sql=true
#spring.jpa.properties.hibernate.format_sql=true

## Database connection pooling properties
# Number of ms to wait before throwing an exception if no connection is available.
spring.datasource.max-wait=10000

# Maximum number of active connections that can be allocated from this pool at the same time.
spring.datasource.tomcat.max-active=10
spring.datasource.tomcat.max-idle=5
spring.datasource.tomcat.min-idle=3

Step 4: Define App.java class under com.sample.app package.

App.java    

package com.sample.app;

import java.util.List;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import com.sample.app.model.Employee;
import com.sample.app.repository.EmployeeRepository;

@SpringBootApplication
public class App {


 public static void main(String args[]) {
  SpringApplication.run(App.class, args);
 }

 @Bean
 public CommandLineRunner demo(EmployeeRepository employeeRepository) {
  return (args) -> {
   Employee emp1 = Employee.builder().firstName("Ram").lastName("Gurram").age(32).salary(100000.23).build();
   Employee emp2 = Employee.builder().firstName("Joel").lastName("Chelli").age(43).salary(60000).build();
   Employee emp3 = Employee.builder().firstName("Gopi").lastName("Battu").age(45).salary(1000000).build();
   Employee emp4 = Employee.builder().firstName("Bomma").lastName("Srikanth").age(39).salary(60000).build();
   Employee emp5 = Employee.builder().firstName("Surendra").lastName("Sami").age(32).salary(100000.23).build();

   employeeRepository.save(emp1);
   employeeRepository.save(emp2);
   employeeRepository.save(emp3);
   employeeRepository.save(emp4);
   employeeRepository.save(emp5);

   
   System.out.println("Running JPA Query");
   List<String> firstNames = employeeRepository.getFirstNames();
   for(String name : firstNames) {
    System.out.println(name);
   }
   
   System.out.println("Running native query");
   firstNames = employeeRepository.getFirstNamesNativeQuery();
   for(String name : firstNames) {
    System.out.println(name);
   }

  };
 }

}

Total project structure looks like below.

Run App.java, you can see below messages in console.    

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)

Ram
Joel
Gopi
Bomma
Surendra
Running native query
Ram
Joel
Gopi
Bomma
Surendra

You can download complete working application from this link.

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