Create one EntityManagerFactory per database in Hibernate 7.4, from persistence.xml, from Java code with PersistenceConfiguration or HibernatePersistenceConfiguration, or from a PersistenceUnitInfo, then open one EntityManager per unit of work with runInTransaction() and callInTransaction().
@NamedStoredProcedureQuery declares a stored procedure call once on an entity and runs it by name. Learn every attribute, parameter modes, result mapping to entities and records, hints and the errors you meet.
EntityManager find() loads an entity with a SELECT or returns null, while getReference() returns a proxy without SQL. See when each runs SQL, when EntityNotFoundException and LazyInitializationException are thrown, and how to set a foreign key without loading the entity.
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