File Systems and Databases

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

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 File Application Toys Addresses Delivery 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. CASE Tools User Interface Application Programs Repository DBMS Database Database Environment

24. 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 Database Application Programs Database contains: User’s Data Metadata Indexes Application Metadata User Interface Applications Database Components

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. Central Computer Centralized Databases

28. Client Network Client Database Server Client Client Server Databases

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. 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