Lesson 1: Database Concepts Environment

• Data


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


  Data processed to be useful in decision making
• Data Hierarchy


  refers to the systematic organization of data, often in a hierarchical form. Data organization involves characters, fields, records, files and so on. 
• bit


  the smallest unit of data
• bit


  has only 2 values
• byte


  8 bits
• byte


  represents one character
• field


  represents a combination of bytes that make up one aspect of a business object
• column / attribute


  another term for field
• record


  a collection of related data fields
• row / tuple


  another term for record
• file


  a collection of related records
• table


  another term for file
• database


  an organized collection of logically related data
• Metadata


  Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and documentation
• • data types
  • field sizes
  • allowable values
  • documentation

  The properties or characteristics of the data
• Database


  Central repository of shared data Data is managed by a controlling agent Stored in a standardized, convenient form
• Database


  requires a Database Management System (DBMS)
• Database Management System (DBMS)


  is a collection of programs that enables users to create and maintain a database
• Database Management System


  a general purpose software system that facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications
• • defining
  • constructing
  • manipulating
  • sharing databases


  What does DBMS facilitate in? What are the process?
• data administrators, system developers, end users, CASE tools, User interface, Application programs, Repository, DBMS, Database

  Components of database
• Repository


  where is the metadata stored
• Database Management System


  manages data resources like an operating system manages hardware resources
• Traditional File Processing


  stores data in separate computer files
• File Processing system


  is a system used to store and manage data that involves each department or area within an organization having its own set of files
• Data redundancy and data isolation


  What are the problems with traditional file processing?
• data redundancy, limited data sharing, program-data dependence


  3 disadvantages of traditional file processing
• Program-data independence, planned data redundancy, improved data sharing, enforcement of standards, improved data quality, better data accessibility / responsiveness, increased productivity of application development, improved decision support

  8 advantages of database approach
• Up-front costs, Ongoing Costs, Organizational Conflict

  3 costs and risks of the database approach
• personal, workgroup, department, enterprise database


  range of database applications
• personal database


  standalone desktop database
• workgroup database


  local area network
• department database


  local area network
• enterprise database


  wide-area network
• <25 users


  size of workgroup database
• 25-100 users


  size of department database
• hundreds or thousands of users

  size of enterprise database
• Flat files


  1960s - 1980s
• Hierarchical


  1970s - 1990s