Hibernate Interview Questions


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1. What is Hibernate?
Hibernate is a powerful, high performance object/relational persistence and query service.
This lets the users to develop persistent classes following object-oriented principles such
as association, inheritance, polymorphism, composition, and collections.
2. What is ORM?
ORM stands for Object/Relational mapping. It is the programmed and translucent
perseverance of objects in a Java application in to the tables of a relational database using
the metadata that describes the mapping between the objects and the database. It works
by transforming the data from one representation to another.
3. What does an ORM solution comprises of?
• It should have an API for performing basic CRUD (Create, Read, Update, Delete)
operations on objects of persistent classes
• Should have a language or an API for specifying queries that refer to the classes
and the properties of classes
• An ability for specifying mapping metadata
• It should have a technique for ORM implementation to interact with transactional
objects to perform dirty checking, lazy association fetching, and other optimization
functions
4. What are the different levels of ORM quality?
There are four levels defined for ORM quality.
i. Pure relational
ii. Light object mapping
iii. Medium object mapping
iv. Full object mapping
5. What is a pure relational ORM?
The entire application, including the user interface, is designed around the relational
model and SQL-based relational operations.
6. What is a meant by light object mapping?
The entities are represented as classes that are mapped manually to the relational tables.
The code is hidden from the business logic using specific design patterns. This approach
is successful for applications with a less number of entities, or applications with common,
metadata-driven data models. This approach is most known to all.