Jakarta Persistence Query Language

<h2 id="examples">Examples</h2>
<p>Example JPA Classes, getters and setters omitted for simplicity.
</p>
@Entity
public class Author {
    @Id
    private Integer id;
    private String firstName;
    private String lastName;
 
    @ManyToMany
    private List<Book> books;
}
 
@Entity
public class Book {
    @Id
    private Integer id;
    private String title;
    private String isbn;
 
    @ManyToOne
    private Publisher publisher;
 
    @ManyToMany
    private List<Author> authors;
}
 
@Entity
public class Publisher {
    @Id
    private Integer id;
    private String name;
    private String address;
 
    @OneToMany(mappedBy = "publisher")
    private List<Book> books;
}

<p>Then a simple query to retrieve the list of all authors, ordered alphabetically, would be:
</p>
SELECT a FROM Author a ORDER BY a.firstName, a.lastName

<p>To retrieve the list of authors that have ever been published by XYZ Press:
</p>
SELECT DISTINCT a FROM Author a INNER JOIN a.books b WHERE b.publisher.name = 'XYZ Press'

<p>JPQL supports named parameters, which begin with the colon (:). We could write a function returning a list of authors with the given last name as follows:
</p>
import javax.persistence.EntityManager;
import javax.persistence.TypedQuery;

...

public List<Author> getAuthorsByLastName(String lastName) {
    String queryString = "SELECT a FROM Author a " +
                         "WHERE a.lastName IS NULL OR LOWER(a.lastName) = LOWER(:lastName)";

TypedQuery<Author> query = getEntityManager().createQuery(queryString, Author.class);
    query.setParameter("lastName", lastName);
    return query.getResultList();
}

<h2 id="hibernate-query-language">Hibernate Query Language</h2>
<p>JPQL is based on the <a href="/facts/Hibernate_(Java)/7hHcgTkB">Hibernate Query Language</a> (HQL), an earlier non-standard query language included in the <a href="/facts/Hibernate_(Java)/7hHcgTkB">Hibernate</a> <a href="/facts/Object-relational_mapping/sjIPEIfq">object-relational mapping</a> library. 
</p><p>Hibernate and the HQL were created before the JPA specification.
As of Hibernate 3 JPQL is a subset of HQL.
</p>
<h2 id="citations">Citations</h2>

<ul><li>Bauer, Christian; King, Gavin; Gregory, Gary (2016), <i>Java Persistence with Hibernate</i> (Second ed.), <a href="/facts/Manning_Publications/opB29j1b">Manning Publications</a>, <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-1617290459</li></ul>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Object-relational_mapping/sjIPEIfq">Object-relational mapping</a></li>
<li><a href="/facts/Hibernate_(framework)/7hHcgTkB">Hibernate (framework)</a></li>
<li><a href="/facts/Jakarta_Persistence/mdw15jQI">Jakarta Persistence</a></li></ul>
<h2 id="external-links">External links</h2>
<ul><li><a href="https://eclipse-ee4j.github.io/jakartaee-tutorial/#the-jakarta-persistence-query-language">Official website</a> 
<ul><li><a href="https://eclipse-ee4j.github.io/jakartaee-tutorial/#full-query-language-syntax">Full Query Language Syntax from The Jakarta EE 8 Tutorial</a></li></ul></li>
<li><a href="https://www.objectdb.com/java/jpa/query">JPA Queries and JPQL - a chapter of the ObjectDB Manual</a></li>
<li><a href="https://torpedoquery.org/">Type safe Hibernate (HQL) query engine - TorpedoQuery</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Bauer, King & Gregory 2016. - Bauer, Christian; King, Gavin; Gregory, Gary (2016), Java Persistence with Hibernate (Second ed.), Manning Publications, ISBN 978-1617290459 <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Bauer, King & Gregory 2016. - Bauer, Christian; King, Gavin; Gregory, Gary (2016), Java Persistence with Hibernate (Second ed.), Manning Publications, ISBN 978-1617290459 <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Bauer, King & Gregory 2016. - Bauer, Christian; King, Gavin; Gregory, Gary (2016), Java Persistence with Hibernate (Second ed.), Manning Publications, ISBN 978-1617290459 <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Jakarta Persistence Query Language open-in-new

Jakarta Persistence Query Language