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Hi, I need help with essay on Object Relational Database. Paper must be at least 3000 words. Please, no plagiarized work!Download file to see previous pages In ORDB, reusability is achieved by using t
Hi, I need help with essay on Object Relational Database. Paper must be at least 3000 words. Please, no plagiarized work!Download file to see previous pages
In ORDB, reusability is achieved by using the techniques of inheritance of types and polymorphism. Every record has unique identity within the object table. Here every record is termed to be active, persistent objects encapsulating both data and methods. The only way to access any data, is through the object methods.
In contrast with this advance database system, the traditional database system like RDBMS (Relational database management system) maps the real world models in the form of entities containing tuples/rows. Each tuple in an entity contains the common set of attributes/columns. Here both entity and its tuples are said to passive, as in order to mutate or access these tuples, data manipulation language or external stored procedures are used. A tuple only contains the data and does not contain any methods. A tuple is not identified by an object id but uniquely identified within an entity, by using data of a column, which is called as the primary key column. In RDBMS, there is no concept of reusability, because there are not any concepts of inheritance and polymorphism.
Encapsulation is achieved through abstract data types (ADTs). In this concept, the object has an interface part and an implementation part. The interface provides specifications of the operations that can be performed on the object. the implementation part consists of the data structure for the ADT and the functions that realise the interface. Only the interface part is visible to other object or users. In ORDB, proper encapsulation is achieved by ensuring that programmers have access only to the interface part. In this way encapsulation provides the form of logical data independence. We can change the internal implementation of an ADT without changing any of the application programs using that ADT. (Connolly &. Begg, p. 686).
Object and Attributes
A uniquely identifiable entity contains both the attributes that describe the state of the real world object and the actions that are associated with the real world objects. A key part of the definition of an object is unique identity. In an ORDBMS, each object has a unique system-wide identifier that is independent of the values of its attributes (that is its state), and is invisible to the user. Two objects could have the same state but would have different identities. When an object is created, it is assigned and Object Identifier (OID) that is unique and invariant, in the sense that it cannot be altered during its lifetime. The OID distinguishes the object from every other object in the system. Once the object is created, this OID will not be reused for any other object, even after the object has been deleted. OID automatically provides entity integrity.
Object methods define the behaviour of the object. They can be used to change the object's state by modifying its attribute values, or to query the value of selected attributes.
Class, Inheritance and Polymorphism
A class is said to be a blue print of an object.