Hibernate

Criteria

https://www.devmedia.com.br/hibernate-api-criteria-realizando-consultas/29627

https://thoughts-on-java.org/common-hibernate-mistakes-cripple-performance/

Default relationship

OneToMany: LAZY ManyToOne: EAGER ManyToMany: LAZY OneToOne: EAGER

The latest version of Hibernate aligns with the above JPA defaults.

@ManyToMany

Join table

A table provides a mapping between two tables. It has foreign keys for each table to define the mapping relationship.

Cascade

You can cascade operatinos

Apply the same operation to related entities.

Cascade Delete

Instrutor 1-1 Hobby - se excluir o instrutor, delete o hobby

Cursos N-N Estudantes - se excluir o estudante, nao exclua os cursos, nao aplica cascade delete aqui.

Entity lifecycle

Detach - If entity is detached, it is not associates with a Hibernate session.

Merge - if instance is detached from session, then merge will reattach to session.

Persist - Transitions new instances to managed state. Next flush / commit will save in db.

Remove - Transitions managed entity to be removed. Next flush / commit will delete from db.

Refresh - Reload / synch object with data from db. Prevents stale data.