The object/relational impedance mismatch occurs because of the fundamental differences between the object and relational models. The three areas of the mismatch
we examined were identity, inheritance, and associations. The impedance mismatch is solved to varying degrees by ORM frameworks.
Applications with basic persistence requirements typically use JDBC because the API is simple and most developers are familiar with it.However, JDBC requires application developers to write, maintain, and test a great deal of repetitive code. JDBC doesn’t handle domain objects directly, requiring you to map domain objects to relational tables.
This problem is further complicated as the domain model increases in complexity. Hibernate is designed to address the shortcomings in direct JDBC and
other ORM frameworks.Using Hibernate doesn’t require that your domain objects implement specific interfaces or use an application server. It supports collections, inheritance, and custom data types, as well as a rich query language.
