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
• Introduction
• Traditional File-based Systems
• Database Approach
• Roles in the Database Environment
• Advantages & Disadvantages of DBMS
Examples of Database Application
• 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
• 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
• 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
– 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
• Data Administrator (DA)– Management of data resources
– Ensure database development support corporate objectives
• Database Administrator (DBA)– Physical realization of database
– More technically oriented
• Database Designers – Logical
• Identifying data
– Physical• Realization of logical database
• Application Programmers– Implement application program for user
• End Users (Naïve and Sophisticated)
Advantages of DBMS
• 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