Data Abstraction

Data Abstraction enables isolation of the object's implementation details from the way it is used. Data Abstraction groups the pieces of data that describe some entity, so that programmers can manipulate that data as a unit.  It helps a programmer to cope with the complexity of data by hiding the details.

In the object database model, each single entity is called an object instance. Each object has a unique unchanging identity. Object identity is characterized by the following features:

Objects are described by classes. A class defines a structure and attributes (fields) of an object. Classes are also used to define hierarchical properties: child and parent relationships.

Object model directly supports references. Note that references establish a connection between objects using their identities. For example:

In this example Pilot object is referenced from a Car object.