Introduction to Database Management Systems:

What is a database and how it emerged when a strong and widely accepted languges like C was there???The answer is simple in language like C the programmer deal with user and DATA directly where as in DBMS the programmer is least bothered of user.Only thing he need to take care of is effective management of  lumbs of data.Here i will try to explain DBMS and RDBMS mostly relating to ‘C’ assuming it as a known language to most people.The first thing that comes to our mind when we say a programming language is ofcourse programs.QUERY is the analogy in a DBMS.Now think about a situation where you have a program to store details of employees of a company,and DB is unknown to you.Then your only option for STORAGE and RETIEVAL of data is files.Any programmer knows the difficulties with files(FLAT files).Say we started using files,we have to store NAME,AGE,QUALIFICATION,EID,SALARY,DEPT,MANAGERID etc.of around 100 employees.Storing might be easy .But HOW about RETRIEVAL????? For retrieval we must store data in a particular fashion so that we ourself has to device a logic,like seperating each employee’s details with some special character,but again if we want any one of employee attributes again those also have to seperated somehow.All these will result in tedious program logic.THIS is HOW DBMS came in.

WHAT is a DBMS and its GOALS??

• Is a computerised record keeping system.
• Which can handle massive amounts of data.
• It provides for STORAGE ,RETRIEVAL,UPDATION of data in an organised manner.

GOALS

• Enforce security of data.
• Concurrency control and Crash recovery.

I would like to elaborate on the points in goals of a DBMS.Consider the case i mentioned earlier,a company and its employees.Who should have access to such a sensitive data?? Senior people only right?or else anyone can change critical details like salary.That is security of data.A DBMS will allow only authorised personnel.This is done using password,encryption etc.But every employee should have the right to check his data.Consider a scene when manager is editing the salary column of an employee,at that time employee is trying to edit his famiy details.Chances are there for an error,but it wont happen because DBMS provides CONCURRENT ACCESS CONTROL.

Def: of a Database Management System:- A DBMS is a collection of programs that facilitates the processof defining,constructing and manipulating databases.Defining a DB means specifying types of data,constructing means storing data and manipulation means updating and querying the Db.

Before finishing the first chapter i have one more relevant point to mention regarding,how a DB helps you.This is a very key point.Think about the same scenerio, the EMPLOYEE.We started without a DB,and used the Flat file system for some time.Now the company made a policy change,that it is going to give all its empoyees a special add on towards salary,which is not taxable,so it needs to be mentioned seperately with each employee.What will you do???With a DBMS the task is simple,this is called logical data independance.

Related posts:

1. RDBMS Chapter-3
2. RDBMS-2
3. Corporate Readiness Program(CRP)@wipro