Found 1301 Articles for MCA

The ANSI-SPARC database architecture is the basis of most of the modern databases.The three levels present in this architecture are Physical level, Conceptual level and External level.The details of these levels are as follows −Physical LevelThis is the lowest level in the three level architecture. It is also known as the internal level. The physical level describes how data is actually stored in the database. In the lowest level, this data is stored in the external hard drives in the form of bits and at a little high level, it can be said that the data is stored in files ... Read More

An Object relational model is a combination of a Object oriented database model and a Relational database model. So, it supports objects, classes, inheritance etc. just like Object Oriented models and has support for data types, tabular structures etc. like Relational data model.One of the major goals of Object relational data model is to close the gap between relational databases and the object oriented practises frequently used in many programming languages such as C++, C#, Java etc.History of Object Relational Data ModelBoth Relational data models and Object oriented data models are very useful. But it was felt that they both ... Read More

Object oriented data model is based upon real world situations. These situations are represented as objects, with different attributes. All these object have multiple relationships between them.Elements of Object oriented data modelObjectsThe real world entities and situations are represented as objects in the Object oriented database model.Attributes and MethodEvery object has certain characteristics. These are represented using Attributes. The behaviour of the objects is represented using Methods.ClassSimilar attributes and methods are grouped together using a class. An object can be called as an instance of the class.InheritanceA new class can be derived from the original class. The derived class contains ... Read More

Database Management System is quite useful compared to the file based management system. However, it does have some disadvantages. Some of those are as follows −More CostlyCreating and managing a database is quite costly. High cost software and hardware is required for the database. Also highly trained staff is required to handle the database and it also needs continuous maintenance. All of these ends up making a database quite a costly venture.High ComplexityA Database Management System is quite complex as it involves creating, modifying and editing a database. Consequently, the people who handle a database or work with it need ... Read More

The systems that are used to organize and maintain data files are known as file based data systems. These file systems are used to handle a single or multiple files and are not very efficient. FunctionalitiesThe functionalities of a File-based Data Management System are as follows −A file based system helps in basic data management for any user.The data stored in the file based system should remain consistent. Any transactions done in the file based system should not alter the consistency property. The file based system should not allow any illegal or potentially hazardous operations to occur on the data.The file based ... Read More

A database is a collection of data, usually stored in electronic form. A database is typically designed so that it is easy to store and access information.A good database is crucial to any company or organisation. This is because the database stores all the pertinent details about  the company such as employee records, transactional records, salary details etc.The various reasons a database is important are −Manages large amounts of dataA database stores and manages a large amount of data on a daily basis. This would not be possible using any other tool such as a spreadsheet as they would simply ... Read More

Spatial data is associated with geographic locations such as cities, towns etc. A spatial database is optimized to store and query data representing objects. These are the objects which are defined in a geometric space.Characteristics of Spatial DatabaseA spatial database system has the following characteristicsIt is a database systemIt offers spatial data types (SDTs) in its data model and query language.It supports spatial data types in its implementation, providing at least spatial indexing and efficient algorithms for spatial join.ExampleA road map is a visualization of geographic information. A road map is a 2-dimensional object which contains points, lines, and polygons ... Read More

Data WarehousingData warehousing is a collection of tools and techniques using which more knowledge can be driven out from a large amount of data. This helps with the decision-making process and improving information resources. Data warehouse is basically a database of unique data structures that allows relatively quick and easy performance of complex queries over a large amount of data. It is created from multiple heterogeneous sources.Characteristics of Data WarehousingIntegratedTime variant Non-volatileThe purpose of Data warehouse is to support the decision making process. It makes information easily accessible as we can generate reports from the data warehouse. It usually contains historical data ... Read More

The Enhanced Entity Relationship Model contains all the features of the Entity Relationship model. In addition to all that, it also contains features of Subclasses, Superclasses and Inheritance.All of these in detail are as follows −SubclassesA subclass is a class derived from the superclass. It inherits the properties of the superclass and also contains attributes of its own. An example is:Car, Truck and Motorcycle are all subclasses of the superclass Vehicle. They all inherit common attributes from vehicle such as speed, colour etc. while they have different attributes also i.e Number of wheels in Car is 4 while in Motorcycle ... Read More

Class hierarchy can be viewed one of two waysSpecialization (Top Down Approach)Generalization (Bottom Up Approach)SpecializationSpecialization is a process of identifying subsets of an entity that shares different characteristics. It breaks an entity into multiple entities from higher level (super class) to lower level (subclass). The class vehicle can be specialized into Car, Truck and Motorcycle ( Top Down Approach)Hence, vehicle is the superclass and Car, Truck, Motorcycle are subclasses. All three of these inherit attributes from vehicle. Moreover, these three share those attributes among themselves while containing some other attributes which make them different.GeneralizationGeneralization is a process of generalizing an entity which ... Read More