1. Chapter 1 The Worlds of Database Systems
File Systems and Databases
Prof. Sin-Min Lee
Dept. of Computer Science

2. Tuesday Thursday
10:15 – 11:30

3. Your evaluation in this course is determined by:
30%
Class Presentation %
Presentation report %
??!

6. Text Book
NARAYAN S. UMANATH & RICHARD W. SCAMELL, DATA MODELING AND DATABASE DESIGN, 2007 Thomson

7. GOOD REFERENCE
A. Silberschatz, H.F. Korth, S. Sudarshan: Database System Concepts, 5th Ed., McGraw-Hill, 2006.

8. William Arthur Ward The mediocre teacher tells.
The good teacher explains.
The superior teacher demonstrates.
The great teacher inspires.
William Arthur Ward

9. Files and Databases
File: A collection of records or documents dealing with one organization, person, area or subject (Rowley)
Manual (paper) files
Computer files
Database: A collection of similar records with relationships between the records (Rowley)
Bibliographic, statistical, business data, images, etc.

10. Introducing the Database
Major Database Concepts
Data and information
Data - Raw facts
Information - Processed data
Data management
Database
Metadata
Database management system (DBMS)

13. Sales per Employee for Each of ROBCOR’S Two Divisions
Figure 1.1

15. Database Systems Types of Database Systems Number of Users Scope
Single-user
Desktop database
Multiuser
Workgroup database
Enterprise database
Scope
Desktop
Workgroup
Enterprise

16. Database Systems Types of Database Systems Location Use Centralized
Distributed
Use
Transactional (Production)
Decision support
Data warehouse

17. Database
A Database is a collection of stored operational data used by the application systems of some particular enterprise (C.J. Date)
Paper “Databases”
Still contain a large portion of the world’s knowledge
File-Based Data Processing Systems
Early batch processing of (primarily) business data
Database Management Systems (DBMS)

18. Why DBMS?
History
50’s and 60’s all applications were custom built for particular needs
File based
Many similar/duplicative applications dealing with collections of business data
Early DBMS were extensions of programming languages
E.F. Codd and the Relational Model
Ashton-Tate and first Microcomputer DBMS

19. File Based Systems File Application Nice Toys Delivery Addresses List
Naughty
Coal
Estimation
Toys
Nice
Just what
asked for

20. From File Systems to DBMS
Problems with file processing systems
Inconsistent data
Inflexibility
Limited data sharing
Poor enforcement of standards
Excessive program maintenance

21. DBMS Benefits Minimal data redundancy Consistency of data
Integration of data
Sharing of data
Ease of application development
Uniform security, privacy, and integrity controls
Data accessibility and responsiveness
Data independence
Reduced program maintenance

22. Terms and Concepts Data independence
Physical representation and location of data and the use of that data are separated
The application doesn’t need to know how or where the database has stored the data, but just how to ask for it
Moving a database from one DBMS to another should not have a material effect on application program
Recoding, adding fields, etc. in the database should not affect applications

23. Database Environment CASE Tools DBMS User Interface Application
Programs
Repository
Database

24. Database Components DBMS Application Programs Design tools Database
===============
Design tools
Table Creation
Form Creation
Query Creation
Report Creation
Procedural
language
compiler (4GL)
=============
Run time
Form processor
Query processor
Report Writer
Language Run time
User
Interface
Applications
Application
Programs
Database
Database contains:
User’s Data
Metadata
Indexes
Application Metadata

25. Types of Database Systems
PC databases
Centralized database
Client/server databases
Distributed databases
Database models

26. PC Databases
E.g.:
Access
FoxPro
Dbase
Etc.

27. Centralized Databases
Computer

28. Client Server Databases
Network
Client
Database
Server

29. Distributed Databases
Location B
Location C
computer
computer
Homogeneous
Databases
computer
Location A

30. Distributed Databases
Client
Heterogeneous
Or Federated
Databases
Remote
Comp.
Local Network
Database
Server
Comm
Server
Remote
Comp.
Client

34. Introducing the Database
Importance of DBMS
It helps make data management more efficient and effective.
Its query language allows quick answers to ad hoc queries.
It provides end users better access to more and better-managed data.
It promotes an integrated view of organization’s operations -- “big picture.”
It reduces the probability of inconsistent data.

36. Figure 1.2 The DBMS Manages the Interaction
Between the End User and the Database
Figure 1.2

38. Introducing the Database
Why Database Design Is Important?
A well-designed database facilitates data management and becomes a valuable information generator.
A poorly designed database is a breeding ground for uncontrolled data redundancies.
A poorly designed database generates errors that lead to bad decisions.

43. Historical Roots Why Study File Systems?
It provides historical perspective.
It teaches lessons to avoid pitfalls of data management.
Its simple characteristics facilitate understanding of the design complexity of a database.
It provides useful knowledge for converting a file system to a database system.

44. Contents of the CUSTOMER File
Figure 1.3

47. Table 1.1 Basic File Terminology

48. Contents of the AGENT File
Figure 1.4

49. A Simple File System
Figure 1.5