1.What is ORM ?
ORM stands for object/relational mapping. ORM is the automated persistence of objects in a Java application to the tables in a relational database.
2.What does ORM consists of ?
An ORM solution consists of the followig four pieces:
- API for performing basic CRUD operations
- API to express ries refering to classes
- Facilities to specify metadata
3.What are the ORM levels ?
The ORM levels are:
- Pure relational (stored procedure.)
- Light objects mapping (JDBC)
- Medium object mapping
- Full object Mapping (composition,inheritance, polymorphism, persistence by reachability)
4.What is Hibernate?
Hibernate is a pure Java object-relational mapping (ORM) and persistence framework that allows you to map plain old Java objects to relational database tables using (XML) configuration files.Its purpose is to relieve the developer from a significant amount of relational data persistence-related programming tasks.
5.Why do you need ORM tools like hibernate?
The main advantage of ORM like hibernate is that it shields developers from messy SQL. Apart from this, ORM provides following benefits:
- Improved productivity
- High-level object-oriented API
- Less Java code to write
- No SQL to write
- Improved performance
- Sophisticated caching
- Lazy loading
- Eager loading
- Improved maintainability
- Improved portability
- ORM framework generates database-specific SQL for you
6.What Does Hibernate Simplify?
Hibernate simplifies:
- Saving and retrieving your domain objects
- Making database column and table name changes
- Centralizing pre save and post retrieve logic
- Complex joins for retrieving related items
- Schema creation from object model
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