Database

A database is a collection of logically related information/data, which is available for one or more users organised in a way, so that it can be easily accessed, managed and updated. It.is actually a place, where related piece of information is stored and various operations can be performed on it by the user.

A database is basically a computer based record/data/information keeping system. Data is raw, unorganized facts and entities relevant to the user need to be processed such as a digital representation of text, numbers, graphical images or sound. The data are stored in such a way that they are independent of the programs used by the people for accessing the data.

e.g. consider the names, telephone numbers and addresses of the relatives etc. You may have recorded this data in an indexed address book or you may have stored it on a hard drive, using application software such as Microsoft Access or OpenOffice.org BASE. Database can be created with the help of given structure:

Information – 

When data is processed, organised, structured or presented in a given context so as to make it useful is called information.

Character –

 The value or data are in the form of letter, number or special character. 

File – 

A file is a collection of related record.

NEED OF A DATABASE

The need for a database arose in the early 1960s in response to the traditional file processing system. In the file processing system, the data is stored in the form of files and a number of application programs are written by programmers to add, modify, delete and retrieve data to and from appropriate files.

However, the file processing system has a number of problems, which are as follows: 

• Some information may be duplicate in several files.

 • The file processing system lacks the insulation between program and data.

• Handling new queries is difficult, since it requires change in the existing application programs or requires a new application program.

• Unable to maintain data standards and does not provide data sharing.

• In this system, all the integrity rules need to be explicitly programmed in all

application programs, which are using that particular data item.

• This system also lacks security features.

To overcome these problems, database system was designed.

COMPONENTS OF A DATABASE

A database consists of several components. Each component plays an important role

in the database system environment.

The major components of database are as follows:

Data

It is raw numbers, characters or facts represented by value. Most of the organisations

generate, store and process large amount of data. The data acts as a bridge between

the hardware and the software. Data may be of different types such as User data,

Metadata and Application Metadata.

Software

It is a set of programs that lies between the stored data and the users of database. It is

used to control and manage the overall computerized database. It uses different types

of software such as MySQL, Oracle etc.

Hardware

It is the physical aspect of computer, telecommunication and database, which consists

of the secondary storage devices such as magnetic disks, optical discs etc., on which

data is stored.

Users

It is the person, who needs information from the database to carry out its primary

business responsibilities.

The various types of users which can access the database system are as follows:

Database Administrator (DBA)

A person, who is responsible for managing or establishing policies for the

maintenance and handling the overall database management system is called DBA.

Application Programmers

The people, who write application programs in programming languages to interact

and manipulate the database are called application programmers.

End-user

A person, who interacts with the database system to perform different operations on

the database like inserting, deleting etc., through menus or forms.

FEATURES OF A DATABASE

Features of database to let you manage your data are as follows:

Tables

It is the building block of any relational database model, where all the actual data is

defined and entered. A database consists of many tables. Tables (relations) consist of

cells at the intersection of records (rows) and fields (columns). Different types of

operations are done on the tables such as storing, filtering, retrieving and editing of

data. It is also known as file.

Field (Data item)

It is an area (within the record), reserved for a specific piece of data. It is the

individual sub-component of one record. It contains set of characters, e.g. customer

number, customer name, street address, city, state, phone number, current address etc.

Field of a table is also known as column or attribute.

Record

It is the collection of data items of all the fields (information) pertaining to one entity

or a complete unit of information, i.e. a person, company , transition etc. Record of a

table is also known as row, entity or tuple.

Queries

It is an inquiry into the database using the SELECT statement. These statements give

you filtered data according to your conditions and specifications indicating the fields,

records and summaries which a user wants to fetch from a database. It allows you to

extract information from the database based on the conditions that you define in query.

DATABASE MANAGEMENT SYSTEM (DBMS)

It is a collection of programs that enables users to create, maintain database and

control all the access to the database. It is a computer based record keeping system.

             • The primary goal of the DBMS is to provide an environment that is both

               convenient and efficient for user to retrieve and store information. It acts as an

               interface between the application program and the data stored in the database.

            • DBMS is a software package that manages database, e.g. MySQL, INGRES,

              MS-ACCESS etc.

            • DBMS is actually a tool that is used to perform any kind of operation on data in

             database. It also maintains data consistency in case of multiple users. The

             purpose of a DBMS is to bridge the gap between information and data. Some

            basic processes that are supported by a DBMS are as follows:

           • Manipulation of the database.

          • Querying the database to retrieve desired information.

          • Updating the content of the database.

 A short list of database applications would include:

        • Payroll

        • Orders

        • Reservation

       • Accounting

       • Catalogues

        • Medical records

       • Inventory

      • Membership

      • Shipping

      • Invoicing

     • Security

     • Mailing

Relational DataBase Management System (rdbms)

RDBMS is a type of DataBase Management System that stores data in the form of

relations (tables). Relational databases are powerful, so they require few assumptions

about how data is related or how, it will be extracted from the database.

An important feature of relational database system is that a single database can be

spread across several tables. Base, Oracle, DB2, SAP, Sybase, ASE, Informix, Access

etc. are the examples ofRDBMS.

WORKING OF A DATABASE

Database is created to operate large quantities of information by input, store, retrieve

and manage the information. It is a centralised location which provides an easy way to

access the data by several users.

Advantages of a Database/DBMS

The centralized nature of database system provides several advantages, which

overcome the limitations of the conventional file processing system.

These advantages are as follows:

• Reduce data redundancy Redundancy means ‘duplication of data’. This

eliminates the replication of data item in different files, extra processingrequired to face the data item from a large database. This also ensures data

consistency and saves the storage space.

• Enforcing data integrity It means that the data contained in the database is

accurate and consistent. Integrity constraints or consistency rules can be

applied to database, so that the correct data can be entered into the database.

• Data sharing The data stored in the database can be shared among multiple users

or application programs.

• Data security The DBMS ensures that the access of database is done only

through an authorized user.

• Ease of application development The application programmer needs to develop

the application programs according to the user’s needs.

• Backup and recovery The DBMS provides backup and recovery sub-system that

is responsible to recover data from hardware and software failures.

• Multiple views of data A view may be the subset of database. Various users may

have different views of the database itself.

• Enforced standards It can ensure that all the data follow the applicable standards.

• Data independence System data descriptions are independent from the

application programs.

Disadvantages of a Database/DBMS

There are many advantages of database, but database also have some minor

disadvantages.

These disadvantages are as follows:

• Cost of hardware and software Through the use of a database system, new costs

are generated due to additional hardware and software requirements.

• Complexity A database system creates additional complexity and requirements.

• Database failures If database is corrupted due to power failure or it is corrupted

on the storage media, then our valuable data may be lost or the system will

stop working.

• Lower efficiency A database system is a multi-user , software, which is less

efficient.

BASIC DATABASE TOOLS

       • org BASE (OO.o BASE) It is a Relational DataBase Management System (RDBMS), which                 establishes the necessary facilities to make open source technology available to the developer                 communities world wide. The default extension ofBASE database is .odb.

    • MS-Access It is also known as Microsoft Office Access which is a powerful tool designed by                Microsoft to create and format databases. The default extension of access database is .accdb.