27 fcs157 l1


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27 fcs157 l1

  1. 1. File Systems and Databases Chapter 1 The Worlds of Database Systems Prof. Sin-Min Lee Dept. of Computer Science
  2. 2. Tuesday Thursday 10:15 – 11:30
  3. 3. ??! Your evaluation in this course is determined by: 30% Class Presentation 10% Presentation report 5%
  4. 6. <ul><li>Text Book </li></ul><ul><li>NARAYAN S. UMANATH & RICHARD W. SCAMELL, DATA MODELING AND DATABASE DESIGN, 2007 Thomson </li></ul>
  5. 7. A. Silberschatz, H.F. Korth, S. Sudarshan: Database System Concepts , 5th Ed., McGraw-Hill, 2006. <ul><li>GOOD REFERENCE </li></ul>
  6. 8. <ul><li>The mediocre teacher tells. </li></ul><ul><li>The good teacher explains. </li></ul><ul><li>The superior teacher demonstrates. </li></ul><ul><li>The great teacher inspires. </li></ul>William Arthur Ward
  7. 9. Files and Databases <ul><li>File: A collection of records or documents dealing with one organization, person, area or subject (Rowley) </li></ul><ul><ul><li>Manual (paper) files </li></ul></ul><ul><ul><li>Computer files </li></ul></ul><ul><li>Database: A collection of similar records with relationships between the records (Rowley) </li></ul><ul><ul><li>Bibliographic, statistical, business data, images, etc. </li></ul></ul>
  8. 10. Introducing the Database <ul><li>Major Database Concepts </li></ul><ul><ul><li>Data and information </li></ul></ul><ul><ul><ul><li>Data - Raw facts </li></ul></ul></ul><ul><ul><ul><li>Information - Processed data </li></ul></ul></ul><ul><ul><li>Data management </li></ul></ul><ul><ul><li>Database </li></ul></ul><ul><ul><li>Metadata </li></ul></ul><ul><ul><li>Database management system (DBMS) </li></ul></ul>
  9. 13. Figure 1.1 Sales per Employee for Each of ROBCOR’S Two Divisions
  10. 15. Database Systems <ul><li>Types of Database Systems </li></ul><ul><ul><li>Number of Users </li></ul></ul><ul><ul><ul><li>Single-user </li></ul></ul></ul><ul><ul><ul><ul><li>Desktop database </li></ul></ul></ul></ul><ul><ul><ul><li>Multiuser </li></ul></ul></ul><ul><ul><ul><ul><li>Workgroup database </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Enterprise database </li></ul></ul></ul></ul><ul><ul><li>Scope </li></ul></ul><ul><ul><ul><li>Desktop </li></ul></ul></ul><ul><ul><ul><li>Workgroup </li></ul></ul></ul><ul><ul><ul><li>Enterprise </li></ul></ul></ul>
  11. 16. Database Systems <ul><li>Types of Database Systems </li></ul><ul><ul><li>Location </li></ul></ul><ul><ul><ul><li>Centralized </li></ul></ul></ul><ul><ul><ul><li>Distributed </li></ul></ul></ul><ul><ul><li>Use </li></ul></ul><ul><ul><ul><li>Transactional (Production) </li></ul></ul></ul><ul><ul><ul><li>Decision support </li></ul></ul></ul><ul><ul><ul><li>Data warehouse </li></ul></ul></ul>
  12. 17. Database <ul><li>A Database is a collection of stored operational data used by the application systems of some particular enterprise (C.J. Date) </li></ul><ul><ul><li>Paper “Databases” </li></ul></ul><ul><ul><ul><li>Still contain a large portion of the world’s knowledge </li></ul></ul></ul><ul><ul><li>File-Based Data Processing Systems </li></ul></ul><ul><ul><ul><li>Early batch processing of (primarily) business data </li></ul></ul></ul><ul><ul><li>Database Management Systems (DBMS) </li></ul></ul>
  13. 18. Why DBMS? <ul><li>History </li></ul><ul><ul><li>50’s and 60’s all applications were custom built for particular needs </li></ul></ul><ul><ul><li>File based </li></ul></ul><ul><ul><li>Many similar/duplicative applications dealing with collections of business data </li></ul></ul><ul><ul><li>Early DBMS were extensions of programming languages </li></ul></ul><ul><ul><li>1970 - E.F. Codd and the Relational Model </li></ul></ul><ul><ul><li>1979 - Ashton-Tate and first Microcomputer DBMS </li></ul></ul>
  14. 19. File Based Systems Naughty Nice Just what asked for Coal Estimation Delivery List Application File Toys Addresses Toys
  15. 20. From File Systems to DBMS <ul><li>Problems with file processing systems </li></ul><ul><ul><li>Inconsistent data </li></ul></ul><ul><ul><li>Inflexibility </li></ul></ul><ul><ul><li>Limited data sharing </li></ul></ul><ul><ul><li>Poor enforcement of standards </li></ul></ul><ul><ul><li>Excessive program maintenance </li></ul></ul>
  16. 21. DBMS Benefits <ul><li>Minimal data redundancy </li></ul><ul><li>Consistency of data </li></ul><ul><li>Integration of data </li></ul><ul><li>Sharing of data </li></ul><ul><li>Ease of application development </li></ul><ul><li>Uniform security, privacy, and integrity controls </li></ul><ul><li>Data accessibility and responsiveness </li></ul><ul><li>Data independence </li></ul><ul><li>Reduced program maintenance </li></ul>
  17. 22. Terms and Concepts <ul><li>Data independence </li></ul><ul><ul><li>Physical representation and location of data and the use of that data are separated </li></ul></ul><ul><ul><ul><li>The application doesn’t need to know how or where the database has stored the data, but just how to ask for it </li></ul></ul></ul><ul><ul><ul><li>Moving a database from one DBMS to another should not have a material effect on application program </li></ul></ul></ul><ul><ul><ul><li>Recoding, adding fields, etc. in the database should not affect applications </li></ul></ul></ul>
  18. 23. Database Environment CASE Tools DBMS User Interface Application Programs Repository Database
  19. 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
  20. 25. Types of Database Systems <ul><li>PC databases </li></ul><ul><li>Centralized database </li></ul><ul><li>Client/server databases </li></ul><ul><li>Distributed databases </li></ul><ul><li>Database models </li></ul>
  21. 26. PC Databases E.g.: Access FoxPro Dbase Etc.
  22. 27. Centralized Databases Central Computer
  23. 28. Client Server Databases Network Client Client Client Database Server
  24. 29. Distributed Databases computer computer computer Location A Location C Location B Homogeneous Databases
  25. 30. Distributed Databases Local Network Database Server Client Client Comm Server Remote Comp. Remote Comp. Heterogeneous Or Federated Databases
  26. 34. Introducing the Database <ul><li>Importance of DBMS </li></ul><ul><ul><li>It helps make data management more efficient and effective. </li></ul></ul><ul><ul><li>Its query language allows quick answers to ad hoc queries. </li></ul></ul><ul><ul><li>It provides end users better access to more and better-managed data. </li></ul></ul><ul><ul><li>It promotes an integrated view of organization’s operations -- “big picture.” </li></ul></ul><ul><ul><li>It reduces the probability of inconsistent data. </li></ul></ul>
  27. 36. Figure 1.2 The DBMS Manages the Interaction Between the End User and the Database
  28. 38. Introducing the Database <ul><li>Why Database Design Is Important? </li></ul><ul><ul><li>A well-designed database facilitates data management and becomes a valuable information generator. </li></ul></ul><ul><ul><li>A poorly designed database is a breeding ground for uncontrolled data redundancies. </li></ul></ul><ul><ul><li>A poorly designed database generates errors that lead to bad decisions. </li></ul></ul>
  29. 43. Historical Roots <ul><li>Why Study File Systems? </li></ul><ul><ul><li>It provides historical perspective. </li></ul></ul><ul><ul><li>It teaches lessons to avoid pitfalls of data management. </li></ul></ul><ul><ul><li>Its simple characteristics facilitate understanding of the design complexity of a database. </li></ul></ul><ul><ul><li>It provides useful knowledge for converting a file system to a database system . </li></ul></ul>
  30. 44. Figure 1.3 Contents of the CUSTOMER File
  31. 47. Table 1.1 Basic File Terminology
  32. 48. Figure 1.4 Contents of the AGENT File
  33. 49. A Simple File System Figure 1.5