Enterprise Application Programming - JPA Overview

This set of flashcards covers key concepts related to JPA (Java Persistence API), including annotations, entity management, and database interactions.

What is the purpose of META-INF/persistence.xml in JPA?

It is used to define the persistence provider and database connection settings for JPA.

Define the annotation @Entity in JPA.

It indicates that the class is a JPA entity and will be mapped to a database table.

What does the @Id annotation signify in a JPA entity?

It designates a field as the primary key for the entity.

What is the function of the @Transient annotation?

It specifies that a field should not be persisted to the database.

List the possible generation strategies available for JPA primary keys.

GenerationType.AUTO, GenerationType.IDENTITY, GenerationType.SEQUENCE, GenerationType.TABLE.

What is the purpose of the @Column annotation in JPA?

It allows customization of the mapping between an entity property and a database column.

Explain the @Temporal annotation and its use.

It is used for entity properties of type java.util.Date or java.util.Calendar to specify how dates should be handled.

What is the purpose of the @Version annotation in JPA?

It is used for optimistic locking to prevent lost updates by ensuring that only one transaction can update a record at a time.

What does the term optimistic locking mean in JPA?

A strategy that allows multiple transactions to read data simultaneously but provides a mechanism to prevent overwriting changes made by others.

What is a MappedSuperClass in JPA?

A superclass that provides a shared mapping for its subclasses, allowing them to inherit common fields and behavior.