What is an embedded ID?

The EmbeddedId annotation is applied to a persistent field or property of an entity class or mapped superclass to denote a composite primary key that is an embeddable class. The embeddable class must be annotated as Embeddable .

What is MapsId?

Map ID is a deprecated term for the unique identifier used to identify a tileset. This identifier is now referred to as a tileset ID.

What is MapsId in hibernate?

The @MapsId annotation tells Hibernate to use the primary key value of the Book entity as the primary key value of the Manuscript entity.

When should I use Mapid?

In short , @MapsId is used to automatically populate the primary key of a child entity if it has the same primary key as of the parent entity.

What is embedded in JPA?

The JPA annotation @Embedded is used to embed a type into another entity.

What is cascade type all?

The meaning of CascadeType. ALL is that the persistence will propagate (cascade) all EntityManager operations ( PERSIST, REMOVE, REFRESH, MERGE, DETACH ) to the relating entities. It seems in your case to be a bad idea, as removing an Address would lead to removing the related User .

What is shared primary key?

There is no such thing as “shared” primary key. It is an ordinary Supertype-Subtype structure; the relation is 1::1; the PKs in the Subtypes are also FKs to the Supertype; in which case the PKs are the same, not “shared” (see Larry’s answer).

How do I use PrimaryKeyJoinColumn?

The PrimaryKeyJoinColumn annotation is used to join the primary table of an entity subclass in the JOINED mapping strategy to the primary table of its superclass; it is used within a SecondaryTable annotation to join a secondary table to a primary table; and it may be used in a OneToOne mapping in which the primary key …

Why do we use JpaRepository in spring boot?

The Spring Data JPA simplifies the development of Spring applications that use JPA technology. With Spring Data, we define a repository interface for each domain entity in the application. A repository contains methods for performing CRUD operations, sorting and paginating data.

What is embedded class?

Embeddable classes are used to represent the state of an entity but don’t have a persistent identity of their own, unlike entity classes. Instances of an embeddable class share the identity of the entity that owns it. Embeddable classes exist only as the state of another entity.