Database Overview:





A database is referred to as the organized collection of data; it is the collection of data that is interrelated. Through database the data can be easily managed and accessed. Data is a collection of raw facts and figures that is not in an arranged form. For example, consider the name, telephone numbers and addresses of the people you know. You may have recorded this data in an indexed address book or on Microsoft Access or Microsoft excel. This is the collection of data with an implicit meaning and hence is a database




The database is used in daily life. For example, if we deposit or withdraw money in a bank; or reserve a hotel or airline or if we search a book in library catalog, these types of activities will definitely include the use of database system. The supermarket also consists of its database system that is updated automatically.

Traditional File approach

Traditional file processing is the first computer based method to handle business applications. In the past, many organization stored data in files on tape or on disks. The data was managed using file processing system. The records in one file are not related to the records in the other file. The business organizations faced the following problems in traditional file approach.

Data Redundancy

In the file processing system, the same data may be duplicated in several files. For example if there are two files “students” and “library”. The file “students” contains the data like roll number, name etc. The file “library” contains roll number and name of those students who get a book from the library along with the information about the book. The data of one student appears in two files and this is called data redundancy, this causes a higher storage.

Data Inconsistency

When the same items of data are held in several different files, the data has to be updated in each separate file when it changes. This is called data inconsistency.

Program data dependence

It is the relationship between data in files and program required to update and maintain the files.

Lack of flexibility

The file processing system is not flexible. That is it cannot easily generate the information that is different from routine. It can take a lot of time to collect the data from different files and write programs to produce the desired information.

Integrity Problems

Integrity means reliability and accuracy of data. The stored data must satisfy certain types of consistency constrains.

Facilities of Database system

A database system is a collection of data and programs. These programs are used to maintain the data. This main purpose of database system is to maintain data and provide it to the user when it is required.

A database system normally provides the following facilities to the user:

  • You can input new files to database
  • You can insert new data in existing files
  • Data can be retrieved from the existing files
  • You can also update data in existing files
  • You can delete the data from existing files
  • The existing files can also be removed from database

Database management system (DBMS)

Through database management system the user can manage his data. DBMS also allows the user to maintain the data. The DBMS is basically a program. The DBMS is a software system that is used to define, construct and manipulate the database for some applications. The definition of database includes the definition of data types, structures and constraints for the data that you are going to store in the database. The database and DBMS software together is known as database system. DBMS uses database manager software to control the database structure.



Components of Database system

There are four major components of a database system.

Data

Data is a collection of raw facts and figures that is not in an arranged form. Data is stored, maintained and is processed by the database system.

Hardware

Hardware is the physical component of the computer system that is used to perform different tasks.

Software

The collection of programs that are used by the computer in the database systems is called software. DBMS is itself software. The three types of software used by DBMS to enable the features of database system are as follows:

Operating system software

The operating system software is used to manage the hardware components.

DBMS software

The DBMS software manages the database in database system.

Application Programs and utilities

The application programs and utilities process the data that is stored in the database.

Personnel

The people that are related to the database system are called personnel such as:

Database Administrator

The database administrators ensure that the database is working properly and are responsible for the whole database system.

Application Programmers

They write the application programs to access the data from database.

End Users

The end users perform different tasks using the application programs on database.

Objectives of DBMS system

  1. Share ability: It means that the data will be shared by different people at the same time.
  2. Availability: It means that user can access the data and DBMS easily
  3. Evolvability: It means that DBMS can change the database because of the change in technology or because of the increase in user requirements.
  4. Database integrity: It ensures that the entered data is consistent.

Advantages of DBMS

  • Independence of data
  • Redundancy Control
  • Consistency Constraints
  • Security of data
  • Database backup and recovery
  • Advanced Capabilities
  • Support complex data relationships




Disadvantages of DBMS

  • High cost of DBMS
  • Additional training
  • Need of data dictionary
  • Higher hardware cost
  • Problems in case of wrong database environment