Transcript Introduction to Database Processing

CH1
Introduction to
Database Processing
CH1. Introduction to DB Processing
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DB technology: One of the hottest career paths
– WWW and Internet
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Enjoyable, interesting and challenging
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DB design and development: art and
engineering
User
Requirement
Physical
Database
Art
DB Design
Engineering
CH1. Introduction to DB Processing
4 Database Examples
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Mary Richards House painting
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Single user Database
Data table : Figure 1-1
Data Entry Form : Figure 1-2
Example report : Figure 1-3
Treble Clef Music
– Multi-user DB ( LAN connection)
– Figure 1-5 : a -Customer Form,
b-Rental Agreement Form,
c- Instrument Form
CH1. Introduction to DB Processing
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State Licensing and Vehicle Registration Bureau
– 52 centers:conduct drivers’ tests and issue and renew
drivers’ license
– 37 offices: sell vehicle registrations
– more than 40 different tables of data
– several of which contain hundreds of thousands of
row of data
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Calvert Island Reservations Centre
– promotional DB: stores data, photos, video, sound,
events and facilities
• Normal users:
• employee:
– customer and reservation DB
CH1. Introduction to DB Processing
CH1. Introduction to DB Processing
Comparison of DB Applications
Type
Example
Typical
Number of
Concurrent
Users
Personal
Mary Richards
Housepainting
1
Typical Size
of Database
< 10 MB
< 100 MB
Workgroup
Treble Clef
Music
<25
Organization
Licensing and
Registration
Hundreds
> 1 Trillion Byte
Internet
Technology
Calvert Island
Reservation
Possibly
Hundreds
Any
CH1. Introduction to DB Processing
The Relationship of Application
Program and the DBMS
DB Application
DBMS
DB
User
•Design and development of Database vs.
Design and development of Database application
•Overlap between DB class and System development
class
CH1. Introduction to DB Processing
File Processing System
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Two File Processing Systems
Customer
Processing
Application
Customer
File
Customer File
user
Rental
Processing
Application
Rental File
user
Rental FIle
CH1. Introduction to DB Processing
Limitations in File Processing System
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Separated and Isolated Data
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Data Duplication
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Application Program Dependency
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Incompatible Files
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The Difficulty of Representing Data in the Users’
Perspectives: e.g. for Fig 1-5(b), several different
files need to be extracted, combined, and
presented together
CH1. Introduction to DB Processing
Database Processing Systems
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Integrated Data
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Reduced Data Duplication
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Program/Data Independence
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Easier Representation of the Users’
Perspectives
CH1. Introduction to DB Processing
Definition of A Database
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A Database is Self-Describing
– Metadata or Data directory or Data dictionary
• Promotes Program/data independence
• easy to change data structure: only change in the data dictionary
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A DB is a Collection of Integrated Records
– Files + Metadata + Indexes + Application Metadata
(Figure 1-11)
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A DB is a Model of a Model
– model of the users’ model
• Mary Richards’s DB is a model of the way in which Mary
Richards views her business
CH1. Introduction to DB Processing
CH1. Introduction to DB Processing
The History of DB Processing
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The Organizational Context
– to resolve problems with the file-processing systems
– At first, database applications were difficult to develop and
vulnerable
– By the mid-1970s, database could efficiently and reliably
process organizational applications
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The Relational Model
– data are stored in a way that minimizes duplicated data and
eliminates certain types of processing errors
– Tables and relationship
CH1. Introduction to DB Processing
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Microcomputer DBMS Products
– dBase II, dBase III Plus, dBase IV
– Access, SALSA, Paradox, Revelation, MDBS, Helix
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Client/Server DB Applications: (LAN)
– File sharing architecture
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Databases Using Internet Technology
– all database applications will be delivered using HTTP,
XML and related technologies
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Distributed Database Processing
– important in theory but have not been widely adopted
– all data are spread over many computers micro, LAN
server, and mainframes (communicate with one another)
CH1. Introduction to DB Processing
– Problems in security and control
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Object Oriented DBMS (ODBMS)
– important in theory but have not been widely used
for business information systems
• difficult to use
• cost and risk require to convert existing database to
ODBMS
• most ODBMS have developed to support engineering
applications
– ODBMS are likely to occupy a niche in commercial
information systems applications
– This text focus on relational model