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Welcome!
Database Systems
COMP- 213
By:
Shahid Mahmood
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Pre-requisites for COMP-213
COMP-200 Data structures andalgorithms
(COMP-102 ProgrammingFundamentals)
(COMP-111 Object OrientedParadigm)
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Warning!Lecture slides are high-level
description of lectures
Relying only upon the slides donot guarantee good grades
inexams
For achieving good grades inexams always attend lectures,Study
books, and explore webresources.
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Agenda
Mission Objective of the course
Significance of DBS
Definition of Database System
Course Contents
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Mission Objective
To provide a fair understandingof database systems, their
architecture and how to developand maintain them
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Real world applications of database
Students records; Employees records
Records about games and players
Collection of pictures, films
Inventory Management systems
Customers info
rmation in a bank,utility service providing company
Database of web pages
Database in scientific applications
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Why computerized database
Due to huge volume of data in thedatabase
For better organization of variousforms of data
Due to query needs
Due to real time database use indifferent applications
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Basics of Database
Data: Data is facts about a thing suchas: People, Objects,
Events, and Ideasetc. (it is incomplete information)
Information: Data in presentable andmeaningful form on which
somedecision can be taken.
Information is Contents of amessage
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Basic Anatomy of Database
Character Field Record File
Database
For Example: Characters {A, S} Fields {Shahid, Pakistan}
Record(Single) {CS 002, Shahid, Asst. Prof.} Files {Personal data,
Salary} Databases {Database of allemployees of CS &IT, Database
ofstudents in CSCS-100}
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Definition of Database
(A) Ashared collection oflogicallyrelated data, designed to meet
theinformation needs ofmultiple users.
(B) A database is a self describing (Metadata) collection
ofintegrated records.
(C) A collection ofinterrelated files from
which information can be retrievedand within which information
can bemanipulated.
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Defining the modeling of Real-
world System
For example: A bank system, A ticketreservation system, A
departmentalstore inventory system etc.,
Modeling: Convert the data involvedinto electronic form +
Convertnecessary structures to keep the datainto electronic form +
Keep all therules and constraints on data inelectronic form as part
of this system
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File Processing Systems
A file processing systems/environment is a collection ofprograms
that perform services forthe end users such as production
ofreports.
They rely upon inter-dependence ofdata and related program
application
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File Processing Systems
Historical Aspects: Initially computerswere used for
Computational/Engineering purposes. Later oncomputers were used for
commercialapplications which resulted intogeneration of file
processingsystems/ environment.
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File Processing System
Various departments of an organization usetheir own data files
and applications
There is program and data interdependence;(Any change in program
or data will unnecessarily effect otherrelated data or
programs)
Necessary data duplication orredundancy
Inconsistent data
No data sharing between various departments
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Comparison of databases
Flat-file Database: The format of adatabase where all data is
stored in aplain text file like the worksheet of MSExcel.
It is appropriate for holding variable length
data.
Relational Database: A database thatgroups data using
commonproperties/attributes found in the dataset. The data is
stored in tables
(relations, entity sets, o
rfile) whichare usually related with each others.
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Advantages of centralized
database systems
+ Data redundancy/ duplication control: ReduceUnnecessary data
repetition
+ Centralized Data Sharing (Multiple data accessibility
and responsiveness)
+ Data consistency: Appearance in the same databasereflects same
image
+ Data Integration: Data are logically related in asingle
relation therefore easy to enquire or update
+ Convenient application development: Newapplications can use
data already stored
+ Independence of programs and data
+ Security of Data: DBA and DBMS take care of it.
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Advantages of centralized
database systems
+ Easy updating and maintenance
+ BetterConcurrency Control: Controlling parallelprocesses
+ Economy of scale
+ Better backup and recovery procedures
+ Provide ease to real-time systems
+ Easy carr
y and transfe
r
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Disadvantages of Database
systems
Costly
Increased vulnerability due to centralizedand integrated
nature
Complex Recovery
Need for explicit backup
Difficult to change the DBMS
Conversion from manual or from file systemis difficult
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Questions?
