Introduction to DBMS

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Introduction
to
Data Base Management System
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Instructor: Faisal Anwer, DCS, AMU
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SOURCE:
Database Systems: Models, Languages, Design, and Application
programming(6th Edition) by Ramez Elmasi, Shamkant B. Navathe + Database
System Concepts (English) 6th Edition by Abraham Silberschatz , S. Sudarshan ,
Henry F. Korth + Freely Accessible Web Resources
Contents
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Basic Definition
Database-system Applications
Approach before Database System
Basic Definition of DBMS and DBMS Functionality
Database System Components
Database Approach of a System
Main Characteristics of the Database Approach
Database Users
Advantages of Using the Database Approach
Additional Implications of Using the Database Approach
Historical development of Database Systems
Decision of using DBMS approach.
Basic Definitions
Data: Known facts that can be recorded and have an
implicit meaning.
 Database: An organized collection of related data.
 Mini-world: Part of the real world about which data is
stored in a database.
 Database Management System (DBMS):
◦ Specially designed software applications that
facilitate the creation and maintenance of a
computerized database.
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Database-System Applications
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Enterprise Information
◦ Sales
◦ Accounting
◦ Human resources and others
Banking and Finance
◦ Banking:
For customer information, loans and
banking transactions
◦ Credit and transactions: For purchases on credit cards
and generation of monthly statements.
◦ And others
Universities
Airlines
Telecommunications and others
Approach before Database systems
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Permanent files.
 application programs manipulate the data files.
Disadvantages:
◦ Data Redundancy
◦ Data inconsistency
◦ Integrity problems
◦ Security problems
◦ Concurrent – access anomalies
…Approach before Database systems
Basic Definitions
◦ DBMS:
 It is a general-purpose software system that
facilitates the processes of defining, constructing,
manipulating, and sharing databases among
various users and applications.
 The primary goal of the DBMS is to provide an
environment that is both convenient and efficient
for user to retrieve and store information
◦ Database System: The DBMS software together
with the data itself is called database system.
DBMS Functionality
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Define a database
 Construct or Load the Database
 Manipulating the database
 Concurrent Processing and Sharing
 Other features:
◦ Protection or Security measures to prevent
unauthorized access
◦ Presentation and Visualization of data
Database approach of a system
With the database approach, we can have the traditional
banking system as shown in the following picture
Example of a Database
(with a Conceptual Data Model)
 UNIVERSITY environment.
Some entities:
 STUDENTs
 DEPARTMENTs (academic)
 PROGRAMMES
 COURSEs
 INSTRUCTORs
Example of a Database
(with a Conceptual Data Model)
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Some relationships:
◦ COURSES are of specific PROGRAMMES
◦ STUDENTs take PROGRAMME
◦ PROGRAMME have prerequisite PROGRAMME
◦ INSTRUCTORs teach COURSES
◦ PROGRAMMES are offered by DEPARTMENTs
◦ STUDENTs ENROLL in DEPARTMENTs
Note: The above could be expressed in the ENTITYRELATIONSHIP data model.
Main Characteristics of the Database
Approach
 Self-describing
nature of a database system: A DBMS
catalog stores the description of the database. The
description is called meta-data. This allows the DBMS
software to work with different databases.
 Insulation between programs and data: Called programdata independence. Allows changing data storage
structures and operations without having to change the
DBMS access programs.
Main Characteristics of the Database
Approach
(cont…)
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Data Abstraction: A data model is used to hide storage
details and present the users with a conceptual view of
the database.
Support of multiple views of the data: Each user may
see a different view of the database, which describes
only the data of interest to that user.
Sharing of data and multiuser transaction processing :
allowing a set of concurrent users to retrieve and to
update the database. Concurrency control within the
DBMS guarantees that each transaction is correctly
executed or completely aborted.
Database Users
Users may be divided into
o Actors on the Scene: Those who actually use and control
the content.
o Workers Behind the Scene: Those who enable the
database to be developed and the DBMS software to be
designed and implemented.
Database Users
Actors on the Scene
 people whose jobs require managing, designing and access to the database
for querying, updating, and generating reports; the database primarily exists
for their use.
 Database administrators: responsible for authorizing access to the
database, for coordinating and monitoring its use, acquiring software, and
hardware resources as needed, controlling its use and monitoring
efficiency of operations. DBA is accountable for problems such as breach
of security or poor response time.
 Database Designers: responsible for identifying the data to be stored in
the database, the structure, the constraints, and functions against the
database. They must communicate with the end-users and understand
their needs.
 End-users: they use the data for queries, reports and some of them
actually update the database content.
 System Analyst and application programmers(Software Engineers) :
System Analysts determine the requirements of end users, especially
naïve and parametric end users. Application programmers implement
these specifications as programs.
Categories of End-users
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Casual : access database occasionally when needed such as middle
and high level managers.
 Naïve or Parametric : they make up a large section of the end-user
population.
 Their main job function revolves around constantly querying and updating the
database using standard types of queries and updates.
 Examples are reservation clerks who do this activity for an entire shift of
operations.
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Sophisticated : these include business analysts, scientists,
engineers, others thoroughly familiar with the system capabilities.
Many use tools in the form of software packages that work closely
with the stored database.
 Stand-alone : mostly maintain personal databases using ready-touse packaged applications. An example is a tax program user that
creates his or her own internal database.
Database Users
Workers Behind the Scene
Associated with the design, development, and operation of the
DBMS software and system environment.
 Tool developers : (Design and implement tools)- Software
packages that facilitate database modeling and design, database
system design, and improved performance.
 DBMS system designers and implementers : Design and
implement the DBMS modules and interfaces as a software
package.
Advantages of Using the Database
Approach
Controlling redundancy in data storage.
 Assuring data consistency.
 Sharing of data among multiple users.
 Restricting unauthorized access to data.
 Providing Storage Structures for efficient Query
Processing
 Providing backup and recovery services.
 Providing multiple interfaces to different classes of
users.
 Representing complex relationships among data.
 Enforcing integrity constraints on the database.
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Additional Implications of Using
the Database Approach
 Potential
for enforcing standards: this is very crucial for
the success of database applications in large organizations
Standards refer to data item names, display formats, report
structures, meta-data (description of data) etc.
 Reduced application development time: incremental time
to add each new application is reduced.
 Availability of up-to-date information: very important for
on-line transaction systems such as airline, hotel, car
reservations.
Historical Development of Database
Technology
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Early Database Applications: The Hierarchical and Network Models were
introduced in mid 1960’s and dominated during the seventies. A bulk of the
worldwide database processing still occurs using these models.
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Relational Model based Systems: The model that was originally introduced in
1970 was heavily researched and experimented with in IBM and the
universities. Relational DBMS Products emerged in the 1980’s.
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Object-oriented applications: OODBMSs were introduced in late 1980’s and
early 1990’s to cater to the need of complex data processing in CAD and
other applications. Their use has not taken off much.
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Data on the Web and E-commerce Applications: Web based application uses
HTML (Hypertext markup language) to create documents with links among
other documents. In the 1990s, electronic commerce (e-commerce) emerged
as a major application on the Web. Parts of the information in web pages are
dynamically extracted from databases. Currently, eXtended Markup Language
(XML) is considered to be the primary standard for interchanging data among
various types of databases and Web pages.
When not to use a DBMS
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Main inhibitors (costs) of using a DBMS:
 High initial investment and possible need for additional
hardware.
 Overhead for providing generality, security, concurrency
control, recovery, and integrity functions.
When a DBMS may be unnecessary:
 If the database and applications are simple, well defined, and
not expected to change.
 If access to data by multiple users is not required.
Summary
DBMS is a specially designed software applications that
facilitate the creation and maintenance of a computerized
database.
 Now a days almost all the enterprises are using DBMS to
manage their data.
 It has distinctive advantages over file handling system.
 Several users are actually involved in databases system.
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