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27 fcs157 l1 27 fcs157 l1 Presentation Transcript

  • File Systems and Databases Chapter 1 The Worlds of Database Systems Prof. Sin-Min Lee Dept. of Computer Science
  • Tuesday Thursday 10:15 – 11:30
  • ??! Your evaluation in this course is determined by: 30% Class Presentation 10% Presentation report 5%
    • Text Book
  • A. Silberschatz, H.F. Korth, S. Sudarshan: Database System Concepts , 5th Ed., McGraw-Hill, 2006.
    • The mediocre teacher tells.
    • The good teacher explains.
    • The superior teacher demonstrates.
    • The great teacher inspires.
    William Arthur Ward
  • 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.
  • Introducing the Database
    • Major Database Concepts
      • Data and information
        • Data - Raw facts
        • Information - Processed data
      • Data management
      • Database
      • Metadata
      • Database management system (DBMS)
  • Figure 1.1 Sales per Employee for Each of ROBCOR’S Two Divisions
  • Database Systems
    • Types of Database Systems
      • Number of Users
        • Single-user
          • Desktop database
        • Multiuser
          • Workgroup database
          • Enterprise database
      • Scope
        • Desktop
        • Workgroup
        • Enterprise
  • Database Systems
    • Types of Database Systems
      • Location
        • Centralized
        • Distributed
      • Use
        • Transactional (Production)
        • Decision support
        • Data warehouse
  • 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)
  • 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
  • File Based Systems Naughty Nice Just what asked for Coal Estimation Delivery List Application File Toys Addresses Toys
  • From File Systems to DBMS
    • Problems with file processing systems
      • Inconsistent data
      • Inflexibility
      • Limited data sharing
      • Poor enforcement of standards
      • Excessive program maintenance
  • 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
  • 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
  • Database Environment CASE Tools DBMS User Interface Application Programs Repository Database
  • 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
  • Types of Database Systems
    • PC databases
    • Centralized database
    • Client/server databases
    • Distributed databases
    • Database models
  • PC Databases E.g.: Access FoxPro Dbase Etc.
  • Centralized Databases Central Computer
  • Client Server Databases Network Client Client Client Database Server
  • Distributed Databases computer computer computer Location A Location C Location B Homogeneous Databases
  • Distributed Databases Local Network Database Server Client Client Comm Server Remote Comp. Remote Comp. Heterogeneous Or Federated Databases
  • 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.
  • Figure 1.2 The DBMS Manages the Interaction Between the End User and the Database
  • 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.
  • 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 .
  • Figure 1.3 Contents of the CUSTOMER File
  • Table 1.1 Basic File Terminology
  • Figure 1.4 Contents of the AGENT File
  • A Simple File System Figure 1.5