This document provides an overview and introduction to file systems and database concepts. It discusses the key differences between file-based systems and database management systems (DBMS), and outlines some of the main components, types, and benefits of database systems, including data independence, data sharing, consistency, and reduced maintenance. It also emphasizes the importance of good database design.

1. File Systems and Databases Chapter 1 The Worlds of Database Systems 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 10% Presentation report 5%

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

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

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

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

16. Database Systems Types of Database Systems Location 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 1970 - E.F. Codd and the Relational Model 1979 - Ashton-Tate and first Microcomputer DBMS

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

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 =============== 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 Central Computer

28. Client Server Databases Network Client Client Client Database Server

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

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

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

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. Figure 1.3 Contents of the CUSTOMER File

47. Table 1.1 Basic File Terminology

48. Figure 1.4 Contents of the AGENT File

49. A Simple File System Figure 1.5