Hibernate Basics

Object-Relational Mapping (ORM) is a programming technique that bridges the gap between the object-oriented world of your application and the relational world of your database. Instead of writing manual JDBC code and SQL queries, an ORM framework like Hibernate allows you to map your Java objects directly to database tables. Each object instance corresponds to a row in the table, and each object field corresponds to a column. Hibernate is a popular, powerful ORM framework that greatly simplifies database persistence in Java applications. To use Hibernate, you first create your Plain Old Java Objects (POJOs), often called entity classes. You then use annotations (like `@Entity`, `@Table`, `@Id`, `@Column`) to tell Hibernate how these classes and their fields map to your database schema. Hibernate takes care of the rest. It provides an API to perform CRUD operations on your objects. When you call a method like `session.save(myObject)`, Hibernate automatically generates and executes the appropriate SQL INSERT statement. When you query for an object, Hibernate generates the SELECT statement, executes it, and populates your POJO with the data from the `ResultSet`. This abstraction allows developers to think in terms of objects rather than database tables and SQL, which can significantly increase productivity and make the data access layer more maintainable. Hibernate also provides many advanced features like caching, lazy loading, and a powerful query language (HQL - Hibernate Query Language), which is an object-oriented version of SQL.