What is Database ?

A database is a collection of information that is organized so that it can easily be accessed, managed and updated.

In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images. In computing, databases are sometimes classified according to their organizational approaches.

The most prevalent approach is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and sub classes.

In today’s World, Data plays a vital role in every business. In our day to day life, we see or interact with many applications and Software’s, every application that we see or work with will have two parts:

To keep it simple GUI is the part where user interacts with (like Facebook application’s – look and feel) and the Data that we see in the application (like Facebook profile, messages, images and videos) are pulled from Database.

End User who interacts with the application may not know how the data is being fetched and where so much of information is stored. Internally all the dynamic content that we see in the application is fetched from Database.

Database and all its components should be designed and configured at the time of application development. 

Once the application is developed we will not be able to make changes to the database structure as every 

change will hugely affect the business application GUI code.

It is very important to make sure that data is securely maintained and accurately stored. So to maintain security and accuracy in database a set of rules / software system is defined and that we call it as 

DBMS (Data Base Management System – which performs all the operations on the database)

                                                                                                 

Database Architecture

Database architecture is logically divided into two types.

1.    Logical two-tier Client / Server architecture

2.    Logical three-tier Client / Server architecture

Two-tier Client / Server Architecture

Two-tier Client / Server architecture is used for User Interface program and Application Programs that runs on client side. An interface called ODBC(Open Database Connectivity) provides an API that allow client side program to call the dbms. Most DBMS vendors provide ODBC drivers. A client program may connect to several DBMS's. In this architecture some variation of client is also possible for example in some DBMS's more functionality is transferred to the client including data dictionary, optimization etc. Such clients are called Data server.

Three-tier Client / Server Architecture

Three-tier Client / Server database architecture is commonly used architecture for web applications. Intermediate layer called Application server or Web Server stores the web connectivity software and the business logic(constraints) part of application used to access the right amount of data from the database server. This layer acts like medium for sending partially processed data between the database server and the client.