Database Management System

 

DBMS

(Database management System)

Data : Collection of meaningless information is called Raw Facts.The Raw Facts and Figures are Called Data which can be store and processed by computer or human being. data can be audio , video , image , text , animation

Information :   The data that is processed is known as information./organized data. Meaningful data.

knowledge : after processing information we get knowledge.

Database : A database is an organized collection of data, so that it can be easily accessed and managed. , collection of related data.

DBA (Database Administrator) – A person who maintain data in file system. That person called "DBA".

Bytes : The logical collection  of bits are called Bytes(8bit = 1 byte )

Data item / DataFields : The logical Collection of bytes are called as data item this is the smallest unit of data item(information) alpha numeric characters are represented in fields.

DBMS - software used to manage DB file in efficient way.

user -> application program -> DBMS -> Database

-----

flat file systems -

• managen by operating system
• good for small size file(KB,MB)
• fails to manage large size file.

problam in file system

• data redundancy
• data inconsistency
• no concurrency
• no security
• difficult to access required data

Representation of Data

1. Bit - the smallest unit of data (0 ,1)
• collection of bits - character / byte ( A - 65, a - 97)
2. Field -collection of character
• ex - modi , 101 , bikaner
3. Record - roll no. - 101 , name - modi , city - bikaner
4. file / table - collection of Records 
5. Databases - collection of files and tables.

Three Ways of Collection Data

·       Traditional File System

·       Conventional File System

·       Database Management System

 

 Traditional File System – That's file system have to lengthy and problematic and In this system data can destroyed by natural disaster. That file system works on Traditional books so that file system called traditional file System.

Conventional File System – In that file system DBA works of EXcel . But In that system Company or firm can't stores store a large data on one file.

Database Management System - DBMS is a software for storing and retrieving users' database is called DBMS. DBMS is a software tool to organize (create, retrieve, update, and manage) data in a database.

The main aim of a DBMS is to supply a way to store up and retrieve database information that is both convenient and efficient.

 Purpose of DBMS 

·        Data redundancy

·        Data inconsistency

·        Difficulty in accessing data

·        Data isolation

·        Integrity Problem

·        Problem in Concurrent access

·        problem with security

 

Advantage of DBMS

·        Sharing of data

·        Independence of data

·        Non-redundency of data

·        Easy of data acess

·        centerlise database management of data

·        Data integrity

·        Data consistency

·        Imposing proper security

·        Easy of data administration

·        easy of recovery

·        simulation acess

 

Characterstics of database Approch

·        Self describing narure of database system.

·        Support multiple view of data

·        Sharing of data multi-user system

·        Inclution between programme and data

 

DBA and their Function

·        Decideing the information contain of the database

·        Define the storage structure and acess stratrgy

·        Define External Schema for users

·        Define Intigrity constranints specification

·        Granting of authorization for data acess

·        define stratrgy for back-up and recovery

·        Monitering and optimizing the performance of the data

·        Installing and upgrading the DBMS and the application tools

Database system architecture/Three tier of database architecture

External / user / presentation Tier :- End-users operate on this tier and they know nothing about any existence of the database beyond this layer. At this layer, multiple views of the database can be provided by the application. All views are generated by applications that reside in the application tier.

internal level / Application / Middle Tier :- At this tier reside the application server and the programs that access the database. For a user, this application tier presents an abstracted view of the database. End-users are unaware of any existence of the database beyond the application. 

 

Internal Data organization / Database  / Data Tier :− At this tier, the database resides along with its query processing languages. We also have the relations that define the data and their constraints at this level.