JPQL UPDATE queries can be used to update entity objects in database. Following is the general syntax:

UPDATE entity_name [[AS] identification_variable] SET update_item {, update_item}*  

UPDATE queries can only be executed in a transaction and the changes are only visible to other users after commit.

Also Update and delete operations (update and delete "queries") can only be executed using the Query#executeUpdate() method:

int executeUpdate()

For select queries we use Query#getResultList() and Query#getSingleResult() methods.

Example

Entity

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

Executing update queries

public class ExampleMain {
    private static EntityManagerFactory entityManagerFactory =
            Persistence.createEntityManagerFactory("example-unit");

    public static void main(String[] args) {
        try {
            persistEmployees();
            findAllEmployees();
            updateITEmployeesSalaries();
            findAllEmployees();
            updateAllEmployeesSalaries();
            findAllEmployees();
        } finally {
            entityManagerFactory.close();
        }
    }

    public static void persistEmployees() {
        Employee employee1 = Employee.create("Diana", 2000, "IT");
        Employee employee2 = Employee.create("Rose", 3500, "Admin");
        Employee employee3 = Employee.create("Denise", 2500, "Admin");
        Employee employee4 = Employee.create("Mike", 4000, "IT");
        Employee employee5 = Employee.create("Linda", 4500, "Sales");
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.persist(employee1);
        em.persist(employee2);
        em.persist(employee3);
        em.persist(employee4);
        em.persist(employee5);
        em.getTransaction().commit();
        em.close();
    }

    private static void findAllEmployees() {
        EntityManager em = entityManagerFactory.createEntityManager();
        System.out.println("-- All employees --");
        Query query = em.createQuery(
                "SELECT e FROM Employee e");
        List<Employee> resultList = query.getResultList();
        resultList.forEach(System.out::println);
        em.close();
    }

    private static void updateITEmployeesSalaries() {
        System.out.println("-- increasing IT employees salaries by 500 --");
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        Query query = em.createQuery("UPDATE Employee e SET e.salary = e.salary + :increment "
                + "WHERE e.dept = :dept");
        query.setParameter("increment", 500d);
        query.setParameter("dept", "IT");
        int rowsUpdated = query.executeUpdate();
        System.out.println("entities Updated: " + rowsUpdated);
        em.getTransaction().commit();
        em.close();
    }

    private static void updateAllEmployeesSalaries() {
        System.out.println("-- increasing all employees salaries by different percentage --");
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        Query query = em.createQuery("UPDATE Employee e SET e.salary = "
                + " CASE "
                + " WHEN e.dept = 'IT' THEN (e.salary * 1.20) "
                + " WHEN e.dept = 'Admin' THEN (e.salary * 1.15) "
                + " ELSE (e.salary * 1.12) "
                + " END");
        int rowsUpdated = query.executeUpdate();
        System.out.println("entities Updated: " + rowsUpdated);
        em.getTransaction().commit();
        em.close();
    }
}

-- All employees --
Employee{id=1, name='Diana', salary=2000.0, dept='IT'}
Employee{id=2, name='Rose', salary=3500.0, dept='Admin'}
Employee{id=3, name='Denise', salary=2500.0, dept='Admin'}
Employee{id=4, name='Mike', salary=4000.0, dept='IT'}
Employee{id=5, name='Linda', salary=4500.0, dept='Sales'}
-- increasing IT employees salaries by 500 --
entities Updated: 2
-- All employees --
Employee{id=1, name='Diana', salary=2500.0, dept='IT'}
Employee{id=2, name='Rose', salary=3500.0, dept='Admin'}
Employee{id=3, name='Denise', salary=2500.0, dept='Admin'}
Employee{id=4, name='Mike', salary=4500.0, dept='IT'}
Employee{id=5, name='Linda', salary=4500.0, dept='Sales'}
-- increasing all employees salaries by different percentage --
entities Updated: 5
-- All employees --
Employee{id=1, name='Diana', salary=3000.0, dept='IT'}
Employee{id=2, name='Rose', salary=4024.9999999999995, dept='Admin'}
Employee{id=3, name='Denise', salary=2875.0, dept='Admin'}
Employee{id=4, name='Mike', salary=5400.0, dept='IT'}
Employee{id=5, name='Linda', salary=5040.000000000001, dept='Sales'}

Example Project

Dependencies and Technologies Used:

• h2 1.4.197: H2 Database Engine.
• hibernate-core 5.3.1.Final: Hibernate's core ORM functionality.
  Implements javax.persistence:javax.persistence-api version 2.2
• JDK 1.8
• Maven 3.5.4