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File Systems and Databases

Chapter 1 Introduction. File Systems and Databases. Class Format. Lectures MUBS e-learning platform Class discussions and presentations Grading Course works Test 10% Class Project 20% Final Exam 70% (80% practical). The mediocre teacher tells. The good teacher explains.

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File Systems and Databases

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  1. Chapter 1 Introduction File Systems and Databases

  2. Class Format • Lectures • MUBS e-learning platform • Class discussions and presentations • Grading • Course works • Test 10% • Class Project 20% • Final Exam 70% (80% practical)

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

  4. 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.

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

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

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

  8. 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)

  9. 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

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

  11. 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

  12. 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

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

  14. 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

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

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

  17. Central Computer Centralized Databases

  18. Client Network Client Database Server Client Client Server Databases

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

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

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