Editing JavaJEEJPA (section)

=Java Persistence Query Language (JPQL)=

JPQL is an extension of EJBQL, which was introduced as part of the EJB 2.0 specification. The query language allows you to write portable queries that work regardless of the underlying data store. Queries in JPQL are not like SQL queries. Where a SQL query deals with tables and columns, a JPQL query deals with objects and attributes. Keywords of JPQL are case-insensitve, entities, identifier, attributes are case-sensitive. Operators are:
* OR
* AND
* &lt;>
* NOT
* BETWEEN
* LIKE
* IN
* EMPTY
* IS NULL
* WHERE

==Examples==
 
 Query q = em.createQuery(<QUERYSTRING>);
 Query q = em.createNamedQuery(<QUERYNAME>); // see @NamedQueries annotation
 List<Type> l = q.getResultList();


 // Query Strings
 FROM Kategorien // Kategorien is the classname or entity name if the name attribute of the entity annotation is used
 SELECT k FROM Kategorien 
 SELECT k FROM Kategorien ORDER BY name // name is attribute of class Kategorien
 SELECT k FROM Kategorien k WHERE k.id.kategorieId = 1006 // id is a composite key
 SELECT x FROM Magazine x WHERE x.y.z = 'abc' OR x.y IS NULL
 SELECT x FROM Magazine x, IN(x.articles) y WHERE y.author = 'Mister B'
 SELECT kadisId, productsOptionsValuesName FROM ballaballa.dbxt.ProductsOptionsValues p

 Query q = emXT.createQuery("SELECT MAX(pov.id.productsOptionsValuesId) + 1 FROM ballaballa.dbxt.ProductsOptionsValues pov");
 Number newPovIdNumber = (Number)q.getSingleResult();

 Query q = emXT.createQuery("DELETE pa FROM ballaballa.dbxt.Produktattribute pa WHERE pa.id.hauptartikelnummer < " + BallaballaProperties.getHandmadeProductsMinKadisID());
 q.executeUpdate();
 
 q = emXT.createNativeQuery("INSERT INTO xt_sport_boeckmann.produktattribute " + " (`hauptartikelnummer`, `bestand`, `farbe_id`, `groesse_id`, `variantennummer`, `sortier_position`, `veroeffentlichungsdatum`,`verfuegbar_ab`) SELECT `hauptartikelnummer`,`bestand`,`farbe_id`,`groesse_id`,`variantennummer`,`sortier_position`,`veroeffentlichungsdatum`,`verfuegbar_ab` FROM " + " sp_kadis_db.produktattribute");
 q.executeUpdate();