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

2. 1 1 Tuesday Thursday 10:15 – 11:30

3. 1 1 ??! Your evaluation in this course is determined by: 30% Class Presentation 10% Presentation report 5%

4. 1 1

5. 1 1

6. 1 1 u Text Book u NARAYAN S. UMANATH & RICHARD W. SCAMELL, DATA MODELING AND DATABASE DESIGN, 2007 Thomson

7. 1 1 A. Silberschatz, H.F. Korth, S. Sudarshan: Database System Concepts, 5th Ed., McGraw-Hill, 2006. u GOOD REFERENCE

8. 1 1 u The mediocre teacher tells. u The good teacher explains. u The superior teacher demonstrates. u The great teacher inspires.

9. 1 1 Files and Databases 4File: A collection of records or documents dealing with one organization, person, area or subject (Rowley) u Manual (paper) files u Computer files 4Database: A collection of similar records with relationships between the records (Rowley) u Bibliographic, statistical, business data, images, etc.

10. 1 1 Introducing the Database 4Major Database Concepts u Data and information l Data - Raw facts l Information - Processed data u Data management u Database u Metadata u Database management system (DBMS)

11. 1 1

12. 1 1

13. 1 1 Figure 1.1 Sales per Employee for Each of ROBCOR’S Two Divisions

14. 1 1

15. 1 1 Database Systems 4Types of Database Systems u Number of Users l Single-user –Desktop database l Multiuser –Workgroup database –Enterprise database u Scope l Desktop l Workgroup l Enterprise

16. 1 1 Database Systems 4Types of Database Systems u Location l Centralized l Distributed u Use l Transactional (Production) l Decision support l Data warehouse

17. 1 1 Database 4A Database is a collection of stored operational data used by the application systems of some particular enterprise (C.J. Date) u Paper “Databases” l Still contain a large portion of the world’s knowledge u File-Based Data Processing Systems l Early batch processing of (primarily) business data u Database Management Systems (DBMS)

18. 1 1 Why DBMS? 4History u 50’s and 60’s all applications were custom built for particular needs u File based u Many similar/duplicative applications dealing with collections of business data u Early DBMS were extensions of programming languages u 1970 - E.F. Codd and the Relational Model u 1979 - Ashton-Tate and first Microcomputer DBMS

19. 1 1 File Based Systems Naughty Nice Just what asked for Coal Estimation Delivery List Application File Toys Addresses Toys

20. 1 1 From File Systems to DBMS 4Problems with file processing systems u Inconsistent data u Inflexibility u Limited data sharing u Poor enforcement of standards u Excessive program maintenance

21. 1 1 DBMS Benefits 4Minimal data redundancy 4Consistency of data 4Integration of data 4Sharing of data 4Ease of application development 4Uniform security, privacy, and integrity controls 4Data accessibility and responsiveness 4Data independence 4Reduced program maintenance

22. 1 1 Terms and Concepts 4Data independence u Physical representation and location of data and the use of that data are separated l The application doesn’t need to know how or where the database has stored the data, but just how to ask for it l Moving a database from one DBMS to another should not have a material effect on application program l Recoding, adding fields, etc. in the database should not affect applications

23. 1 1 Database Environment CASE Tools DBMS User Interface Application Programs Repository Database

24. 1 1 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. 1 1 Types of Database Systems 4PC databases 4Centralized database 4Client/server databases 4Distributed databases 4Database models

26. 1 1 PC Databases E.g.: Access FoxPro Dbase Etc.

27. 1 1 Centralized Databases Central Computer

28. 1 1 Client Server Databases Network Client Database Server

29. 1 1 Distributed Databases computer Location A Location C Location B Homogeneous Databases

30. 1 1 Distributed Databases Local Network Database Server Client Comm Server Remote Comp. Remote Comp. Heterogeneous Or Federated Databases

31. 1 1

32. 1 1

33. 1 1

34. 1 1 Introducing the Database 4Importance of DBMS u It helps make data management more efficient and effective. u Its query language allows quick answers to ad hoc queries. u It provides end users better access to more and better-managed data. u It promotes an integrated view of organization’s operations -- “big picture.” u It reduces the probability of inconsistent data.

35. 1 1

36. 1 1 Figure 1.2 The DBMS Manages the Interaction Between the End User and the Database

37. 1 1

38. 1 1 Introducing the Database 4Why Database Design Is Important? u A well-designed database facilitates data management and becomes a valuable information generator. u A poorly designed database is a breeding ground for uncontrolled data redundancies. u A poorly designed database generates errors that lead to bad decisions.

39. 1 1

40. 1 1

41. 1 1

42. 1 1

43. 1 1 Historical Roots 4Why Study File Systems? u It provides historical perspective. u It teaches lessons to avoid pitfalls of data management. u Its simple characteristics facilitate understanding of the design complexity of a database. u It provides useful knowledge for converting a file system to a database system.

44. 1 1 Figure 1.3 Contents of the CUSTOMER File

45. 1 1

46. 1 1

47. 1 1 Table 1.1 Basic File Terminology

48. 1 1 Figure 1.4 Contents of the AGENT File

49. 1 1 A Simple File System Figure 1.5

50. 1 1

51. 1 1

52. 1 1

53. 1 1

54. 1 1

55. 1 1

56. 1 1

57. 1 1