JPA's EntityManager createQuery() vs createNamedQuery() vs createNativeQuery()

Question

Can anyone please explain me the differences between following methods of JPA\'s EntityManager: createQuery(), createNamedQuery() and createNativeQuery() And also explain me on

Answer 1

CreateQuery is used to create an JPQLqueries

createNamedQuery is used to define queries with name in mapping file or annotation, example: obj.createNamedQuery("entity.findbycode",Something.class)

createNativeQuery is used to execute native/pure SQL queries.

Answer 2

• The createQuery method is used to create dynamic queries, which are queries defined directly within an application’s business logic. Example:

  public List findWithName(String name) {
  return em.createQuery(
  "SELECT c FROM Customer c WHERE c.name LIKE :custName")
  .setParameter("custName", name)
  .setMaxResults(10)
  .getResultList();
  }
  

• The createNamedQuery method is used to create static queries, or queries that are defined in metadata by using the javax.persistence.NamedQuery annotation. The name element of @NamedQuery specifies the name of the query that will be used with the createNamedQuery method. The query element of @NamedQuery is the query:

  @NamedQuery(
  name="findAllCustomersWithName",
  query="SELECT c FROM Customer c WHERE c.name LIKE :custName"
  )
  

Here’s an example of createNamedQuery, which uses the @NamedQuery:

    @PersistenceContext
    public EntityManager em;
    ...
    customers = em.createNamedQuery("findAllCustomersWithName")
    .setParameter("custName", "Smith")
    .getResultList();

• The createNativeQuery Create an instance of Query for executing a native SQL statement. here are some reasons to choice createNativeQuery:

  • Low level access, which means that you can optimize and handle the mapping by yourself; with SQL you actually access the database table while with JPQL you access the entity objects;
  • Maybe you do not want to learn JPQL if you already know SQL
  • You already have the queries written in SQL, and do not have resources/time to port them to JPQL

For more details visit those links:

Creating Queries Using the Java Persistence Query Language

JPA why use createNamedQuery

Why do we need to create native query?

Answer 3

1. CreateQuery: Used to create an JPQL
2. createNamedQuery: Used to define queries with name in mapping file or annotation go to this
3. createNativeQuery: Used to execute native/pure SQL queries Example