JPA Part 2

Learning Objectives

1. JPQL Query types
   • Be able to explain the purpose of JPQL and how it differs from SQL.
   • What is the difference between TypedQuery and Query and when to use them.
   • Be able to demonstrate and explain how to use NamedQueries.
   • Be able to demonstrate native queries and explain the purpose.
2. JPQL result types
   • Be able to explain the difference between the methods getResultList and getSingleResult.
   • Be able to explain the difference between the methods setFirstResult and setMaxResults.
   • Be able to explain getFirstResult and getMaxResults methods.
3. JPA relations between entities (1)
   • Be able to explain and demonstrate the use of the annotations @OneToOne, @OneToMany, @ManyToOne.
4. JPA relations between entities (2)
   • Be able to explain the concepts identifying and non-identifying relationships.
   • Be able to explain and show the difference between uni-directional and bi-directional relationships.
   • Explain the use of @MapsId annotation.
5. JPA annotations.
   • explain and demonstrate the use of Enumerated annotation to map Java enum types to database columns.
   • explain and demonstrate the use of Temporal annotation to map Java Date and Calendar types to database columns.
   • explain the use of @Transient annotation.
6. JPQL
   • Be able to explain the difference between the methods setParameter and setParameters.
   • Be able to explain the difference between the methods executeUpdate and executeQuery.
   • Be able to explain the methods isBound.
7. Cascading and data fetching.
   • explain and demonstrate the difference between FetchType.EAGER and FetchType.LAZY.
   • explain and demonstrate the difference between CascadeType.ALL and CascadeType.PERSIST.
   • explain and demonstrate the difference between orphanRemoval=true and orphanRemoval=false.
8. Be able to explain and demonstrate JPA relation @ManyToMany.
   • explain the @ManyToMany annotation.
   • explain and demonstrate the difference between owning and inverse side of a relationship.
   • explain and demonstrate the @JoinColumn annotation to specify the foreign key column name.
9. DTO projections in JPQL
   • Explain what an DTO is
   • Explain and demonstrate the use of DTO projections in JPQL queries