Reviewer

• Data


  Facts, text, graphics, images, sound, video segments
• Information


  Data processed to be useful in decision making; actionable
• Data Hierarchy


  • Bit
  • Byte
  • Field
  • Record
  • File
  • Database
• Bit


  The smallest unit of data; has only two values (i.e. 1, 0)
• Byte


  8 bits make up one byte, which represents one character (i.e. A, 1, ?)
• Field


  Represents a combination of bytes that make up one aspect of a business object (i.e. student number, student name); also called column/attribute
• Record


  A collection of related data fields; also referred to as row/tuple
• File


  A collection of related records; also referred to as table
• Database


  An organized collection of logically related data
• Components of the Database Environment

  • CASE Tools
  • Repository
  • Database Management System (DBMS)
  • Database
  • Application Programs
  • User Interface
  • Data Administrators
  • System Developers
  • End Users

  
• CASE Tools


  Computer-aided software engineering
• Repository


  Centralized storehouse of metadata
• Database Management System (DBMS)


  Software for managing the database

  
• Database


  Storehouse of the data
• Application Programs


  Software using the data
• User Interface


  Text and graphical displays to users
• Data Administrators


  Personnel responsible for maintaining the database
• System Developers


  Personnel responsible for designing databases and software
• End Users


  People who use the applications and databases
• The Database


  • Central repository of shared data
  • Data is managed by a controlling agent
  • Stored in a standardized, convenient form
  • Requires a Database Management System (DBMS)

  
• Database Management System (DBMS)

  • A collection of programs that enables users to create and maintain a database
  • A general purpose software system that facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications

  
• Metadata

  • Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and documentation
  • Data that describes data and it is stored in a repository
• Traditional File Processing

  1. File processing system where data are stored for each individual application in an organization

  2. Each department or area within an organization has its own set of files, often creating data redundancy and data isolation

  3. No overall map, plan, or model guided application growth
• Disadvantages of Traditional File Processing

  • Data Redundancy (Duplication of Data)
  • Program Data Dependence
  • Limited Data Sharing – no centralized storage of data
• Data Redundancy


  • Inefficient use of storage space
  • Data integrity may be compromised
• Program Data Dependence


  • Excessive program maintenance
  • Lengthy development of program
• Advantages of Database Approach

  • Program-Data Independence
  • Planned Data Redundancy
  • Improved Data Sharing
  • Enforcement of Standards
  • Improvement Data Quality
  • Better Data Accessibility/ Responsiveness
  • Increased Productivity of Application Development
  • Improved Decision Support

  
• Program-Data Independence

  • Metadata stored in a repository, so applications don't need to worry about data formats
  • Results in reduced program maintenance
• Planned Data Redundancy

  • Leads to increased data integrity/consistency
  • Minimal data duplication
• Improved Data Sharing

  Different users get different views of the data
• Enforcement of Standards


  All data access is done in the same way
• Improvement Data Quality


  Constraints, data validation rules
• Better Data Accessibility/ Responsiveness

  Use of standard data query language (SQL)
• Increased Productivity of Application Development


  • Developer can focus on specific functions
  • Provision of high level productivity tools
• Improved Decision Support


  Databases expressly designed for decision support applications
• Cost and Risk of the Database Approach

  • Up-front Cost
  • Ongoing Cost
  • Organizational Conflict
• Up-front Cost


  • Installation Management Cost and Complexity
  • Conversion Cost
• Ongoing Cost


  • Requires new, specialized personnel
  • Need for explicit backup and recovery
• Organizational Conflict


  Conflicts in reaching consensus on data definitions and ownership
• The Range of Database Applications

  • Personal Database
  • Workgroup Database
  • Department Database
  • Enterprise Database