JPA 1

Transient Field
- stop an entity property from being persisted


JPA (Java Persistence API)
@Entity
@Id
@IdClass
@Embeddable
@Embeddable annotation is used to designate persistent objects that need not have an identity of their own.


Entity Relationships
@OneToOne
   @OneToOne(mappedBy="xxx", optional="true/false");

@OneToMany
@ManyToOne

@ManyToMany