Some confusion exists about what is inherited in an object hierarchy. In simple terms, data structures and behaviors are the only things that are inherited. This means that a developer can inherit a file dialog from one object and a set of GUI controls from another, thus creating a new object that combines a file dialog with the GUI controls. Encapsulation Encapsulation is one of the features of the object oriented approach that has the most meaning for relational databases. Unlike a traditional relational implementation where data is manipulated by external applications, the object technology approach moves the data access out of external applications and associates them with their base objects.
Encapsulation makes the data and methods private within an object.
Developers can modify encapsulated data and methods without disturbing other portions of the application, as long as the external interfaces remain unchanged. Encapsulation has a drawback, however. We must ask ourselves whether it is a good thing that data may only be accessed through predefined behaviors. One of the relational database's primary selling points is the ability to formulate adhoc queries with SQL quickly, independent of data. Polymorphism Polymorphism is the ability of different objects to receive the same message and behave in different ways.