Database introduction

Introduction
 Database integral part of our day to day life
 Collection of related database
 Database Management System : software
managing and controlling access to the
database.
 Database system : collection of application
interracting with database

Example of use of database systems
A database is accessed when :
 Purshasing in a supermarket ( item price)
 Purchase using credit cards ( valid cards)
 Inquiries about a holliday (flight details)
 Make a loan (library)
 Rent video ( detail info on each video)
 Online bookstore( book details)

Dtabase in the dev cycle
Project
Identifcation
and Selection
Project
Initiation
and Planning
Analysis
Logical
Design
Physical
Design
Implementation
Maintenance

Database
 A repository of data simultaneously used by many
users (a shared ressource).
 Collection of logically related data.
 Description of this data (data dictionary)
 BDMS
Software interracting with :
 Users
 Application programs
 database

 BDMS
Software interracting with :
 Users
 Application programs
 Database
DBMS allows users (using a query language):
 Insert
 Update
 Delete
 Retrive data from DB

Database application programs
Computer program that allow
users to interact with the DB
through DBMS.

DBMS environment

Hardware :Computer systems that DBMS and
application programs run on.

Software: DBMS,application programs, operating
system, network software(if DBMS used over
network).

Data ( operational data and meta-data)

Procedures: instruction and rules that govern use of
database

People: DB designer, administrators , programmers
and end users

DBMS architecture
2 layer architecture Client-Server
 The client that runs the application and the server that
handles the database back-end
 Multiple users able to access the DB simultanousely.
 Server is processing data while the client for business
logic and presentation.

DBMS architecture
3 layer architecture
 User Interface layer ( runs on the user´s client)
 Business logic (middle layer) and data processing
layer. Runs on a server called ”application server”.
 DBMS ( store data ) , may run on a separate server
called ”database server”

3 layer architecture advantages
 Thin client (less hardware) , client only handling
presentation logic.This means a little communication
needed between the client(browser) and the middle tier.
 Separating the core business logic from the database
functions
 Modularity : Easy to modify or replace one tier without
affecting the other tiers
 Easier load balancing
 Maps quite naturally to the web environment
 Security : middle tier protecting the DB.
 Scalabale : add as many middle tier as needed

Functions of a DBMS
 Data storage , retrieval and update
 A user-accessible Catalog
 Hold data about the structure of database , users , applications and so on
 Transaction support
 Ensure that all the updates are made or that none of them are made
 Concurrency control services
 Enable many users to access shared data concurrently
 Recovery services
 When transaction fails, DB revovered to a consistent state

Functions of a DBMS
 Autorization services
 Only special part could have access to info
 Support for data communication
 Terminal at remote locations can communicate with host of DBMS through
network
 Integrity Services
 Stored data are consistent and correct
 Services to promote Data Independence
 Utility Services
 Utility program help manage the DB effectively

Advantages of DBMS
 Control of data redundancy (duplication)
 Eliminate redundency where possible ,
 Data consistency
 Data stored in more than once , system can ensure that all copies
of the data are kept consistent
 Sharing of data
 By all authorized users
 Improved data integrity
 Rules that DB is not permitted to violate
 User define data and DBMS enforce it
 Improved maintenance through data independence
 Make application immune to changes in data description

Database introduction

More Related Content

What's hot (19)

Similar to Database introduction (20)

More from Harry Potter (20)

Recently uploaded (20)

Database introduction