The relational model describes a system by information, using relations, attributes, domains, and tuples. In contrast, the object-oriented model describes a system using objects that define identity, state, behavior, encapsulation, and inheritance. An object's identity, as the name implies, distinguishes an object from the other objects. The state defines the current value of an object. An object's behavior is a collection of methods and interfaces that responds to messages.
Encapsulation hides the data from external entities, forcing data access to occur through methods.
Inheritance allows objects to take advantage of features and functions of other objects. What's more, views now in the relational model exist as object attributes and relational integrity constraints would have to map to type-based inheritance. The idea is to model the database as an object-oriented or relational database, then switch the model depending on your requirements. UMA provides such subsystems as a Model Explorer and an Object Property Inspector. Thus, we end up supporting two instances of the same schema.