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Text Book
1. Ramakrishna R and J Gerke ;
McGrawHill Reference Book
1. R Elmasri & S B Navate;
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Data: raw facts Being stored and retrieved
Not to be processed to reveal their meaning to theuser
Information: processed data
Key to good decision making
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A set of information held in acomputer
One or more large structured sets ofpersistent data, usually associatedwith software to update and query thedata
A collection of data arranged for easeand speed of search and retrieval
Introduction to Database Systems
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Data: Known facts that can be recorded and
that have implicit meaning
Database: Collection of related data
Ex. the names, telephone numbers and
addresses of all the people you know
Database Management System: A
computerized record-keeping system
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Library catalogues Medical records
Bank accounts
Stock market data
Personnel systems
Product catalogues
Telephone directories
Train timetables Airline bookings
Credit card details
Student records
Customer histories
Stock market prices
Discussion boards
and so on
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Network Data Model
(mid 70s)File System
(before 70s)
Hybrid model
(mid 80s)
Relational model
(late 80s)
Object-oriented
model (mid 90s)
Object-relational
model (late 90s)
data
modeling
capacity
data
management
facilities
* adapted from the material in http://www.ktdata.co.kr/ktdata/kthome7/zeus_5.htm
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Database is a collection of data describing objects and theirrelationships
However a DBMS is software designed to assist in
maintaining and utilizing large collection of data.
Database Management System = DBMS
A collection of files that store the data
A big C program written by someone else that accesses and
updates those files for you
Relational DBMS = RDBMS
Data files are structured as relations (tables)
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Introduction to Database Systems
A very large, integrated collection of data.
Models real-world enterprise.
Entities (e.g., students, employee)Attributes (e.g., student-roll,name,age,address,class
etc.)
Relationships (e.g., Teacher is teaching student)
A Database Management System (DBMS)is asoftware
package designed to store and manage databases.
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Introduction to Database Systems
Database Management System (DBMS): software
system (collect of software) help to manage the data
contentsManages Database structure
Controls access to data
Contains query language
Application software DBMS Database
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Goals of a Database Management System:
To provide an efficient as well as a convenient environment for
accessing data in a database
Enforce information security: database security, concurrency
control, crash recovery
It is a general purpose facility for:
Defining database
Constructing database
Manipulating database
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Introduction to Database Systems
Backend for traditional database applications
Backend for large Websites
Backend for Web services
Amazon
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Sure we can! Start by storing the data in files:
students.txt courses.txt professors.txt
Now write C or Java programs to implementspecific tasks
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Enroll Ram in BBA108:
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Read students.txt
Read courses.txt
Find&update the record Ram
Find&update the record BBA108Write students.txt
Write courses.txt
Write a C/Java program to do the following:
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Large data sets (say 50GB)
Simultaneous access by many users Lock students.txt what is the problem ?
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Read students.txtRead courses.txtFind&update the record Mary JohnsonFind&update the record CSE444Write students.txtWrite courses.txt
CRASH !
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program-1
data description-1
program-2
data description-2
program-3
data description-3
File-1
File-2
File-3
Application program-1with data semantics
Application program-2with data semantics
Application program-3with data semantics
Description
Manipulation
Control
Queries Database
File System approach
DBMS approach
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Data Raw Facts
Field
Group of characters with specific meaning Record
Logically connected fields that describe aperson, place, or thing
File and file folder Collection of related records
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fieldrecord
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Figure 1.5
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Each application must move large datasetsbetween main memory and secondary storage(must deal with, e.g., buffering, page-oriented
access, etc).
Each application must deal with some methodof identifying all data items in case the available
addressing mode is not sufficient (e.g., 32-bitaddressing cannot directly access more than4GB).
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advantages disadvantages
FMS
Simpler to use Less expensive
Typically no multi-user access Limited to smaller databases
Limited functionality
Decentralization of data
Redundancy and integrity issues
Crash Recovery
DBMS Greater flexibility
Greater processing power
Ensures data integrity
Supports simultaneousaccess
Provides backup and
recovery controls
Advanced security
Supports Transaction
Difficult to learn
Packaged separately from the
OS
Slower processing speeds Requires skilled administrators
Expensive
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33Data files
Database server
(someone elses
C program)Applications
connection
(ODBC, JDBC)
Two tier system or client-server
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Many computingapplications deal withlarge amounts of
information
Database systemsgive a set of tools for
storing, searchingand managing thisinformation
Databases are a coretopic in computerscience and IT
Basic concepts andskills with databasesystems are part ofthe skill set you will
be assumed to haveas a BBA graduate
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A large amount of data,
Concurrent access by many users,
Fast access,
Consistent data update, Role-based security,
Robust against hardware failures and
OS crashes.
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*Application programs no details of datarepresentation & storage
* High-quality data compression schemes,
* Fast data retrieval and search algorithms.
* Programs can prevent invalid queries from
being executed,
* Access control can be enforced.
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* The DBA can optimize the organizationof the data to facilitate its uses.
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Advantages of DBMS
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Slow Response- need to update data in real time.
- Can be slow & complex to extract data for reports
Application may need to manipulate the data in waysnot supported by query Language. Eg flexible analysisof text data
intoday's scenario
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Open source Databases
MySQL
PostgreSQL
Commercial Databases
MS SQL Server MS Access
ORACLE
DB2
Informix