Chapter 1
Introduction to Databases
Thomas Connolly, Carolyn Begg, Database System, A
Practical Approach to Design Implementation and
Management, 4th Edition, Addison Wesley
Pg 3 ~ 26
Learning Outcomes
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Introduction
Traditional File-based Systems
Database Approach
Roles in the Database Environment
Advantages & Disadvantages of DBMS
Examples of Database Application
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Purchases from the supermarket
Purchases using credit card
Booking a holiday at the travel
Using the local library
Taking out insurance
Using the Internet
Studying at university
File-based Definition
• Collection of application program that
perform services for the end users (e.g
reports)
• Program defines and manages it’s own data
File-based Processing
Limitations of File-based
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Separation and isolation
Duplication
Program & data dependence
Fixed queries
Proliferation of application programs
Database
• Definition
– A collection of self-describing and integrated
data files
• System catalog
– Meta data
– Data dictionary
– Overhead data
• Data abstraction
Database Approach
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Data definition language (DDL)
Data manipulation language (DML)
Structured query language (SQL)
Security system
Integrity system
Concurrency control system
Backup & recovery system
View mechanism
Database Management System
(DBMS)
DBMS Environment
• Hardware
– Client-server architecture
• Software
– dbms, os, network, application
• Data
– Schema, subschema, table, attribute
• People
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Data administrator & database administrator
Database designer: logical & physical
Application programmer
End-user: naive & sophisticated
• Procedure
– Start, stop, log on, log off, back up, recovery
Roles in the Database Environment
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Data Administrator (DA)
– Management of data resources
– Ensure database development support corporate objectives
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Database Administrator (DBA)
– Physical realization of database
– More technically oriented
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Database Designers
– Logical
• Identifying data
– Physical
• Realization of logical database
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Application Programmers
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Implement application program for user
End Users (Naïve and Sophisticated)
Advantages of DBMS
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Control redundancy
Consistency
Integrity
Security
Concurrency control
Backup & recovery
Data standard
More information
Data sharing & conflict control
Productivity & accessibility
Economy of scale
Maintenance
Limitations of DBMS
• Complexity
• Size
• Cost
– Software
– Hardware
– Conversion
• Performance
• Vulnerability