chap1im

• Data


  Raw facts
• Information


  Result of processing raw data to reveal meaning
• Accurate, relevant, and timely information is the key to good decision making
• Database


  Shared, integrated computer structure that stores a collection of end-user data and metadata
• Database management system (DBMS)

  Collection of programs that manages the structure and controls access to the data in a database
• DBMS

  • It is the intermediary between the user and the database
  • It enables data to be shared
  • It integrates many users' views of the data
• Advantages of a DBMS

  • Improved data sharing
  • Improved data security
  • Better data integration
  • Minimized data inconsistency
  • Improved data access
  • Improved decision making
  • Increased end-user productivity
• Types of databases based on number of users

  • Single-user database
  • Multiuser database
• Types of databases based on location

  • Centralized database
  • Distributed database
• Types of databases based on expected use

  • Operational database
  • Data warehouse
• Types of data


  • Unstructured data
  • Structured data
  • Semistructured data
• Database design


  • Focuses on the design of the database structure used for end-user data
  • Designer must identify the database's expected use
  • Well-designed database facilitates data management and generates accurate and valuable information
  • Poorly designed database causes difficult-to-trace errors
• Structural dependence


  Access to a file is dependent on its own structure
• Structural independence


  Ability to change the file structure without affecting data access
• Data dependence


  Data access changes when data storage characteristics change
• Data independence

  Data storage characteristics do not affect data access
• Logical data format


  How humans view the data
• Physical data format


  How the computer must work with the data
• Data redundancy


  Same data stored unnecessarily in different places
• Data inconsistency

  Different and conflicting versions of the same data occur at different places
• Data anomalies


  Abnormalities when all changes in redundant data are not made correctly
• Most users lack the skill to properly design databases, despite multiple personal productivity tools being available
• Good data modeling facilitates communication between the designer, user, and the developer
• Database system


  Defines and regulates the collection, storage, management, and use of data
• Major parts of a database system

  • Hardware
  • Software
  • People
  • Procedures
  • Data
• Types of software required in a database system

  • Operating system software
  • DBMS software
  • Application programs and utility software
• People involved in a database system

  • System and database administrators
  • Database designers
  • Systems analysts and programmers
  • End users
• Procedures


  Instructions and rules that govern the design and use of the database system
• DBMS functions


  • Data dictionary management
  • Data storage management
  • Performance tuning
  • Data transformation and presentation
  • Security management
  • Multiuser access control
  • Backup and recovery management
  • Data integrity management
  • Database access languages and application programming interfaces
  • Database communication interfaces
• Database system provides a framework in which strict procedures and standards are enforced
• Role of human changes from programming to managing the organization's resources
• Database system enables more sophisticated use of the data
• Data structures created within the database and their relationships determine the effectiveness of the database system
• Disadvantages of database systems

  • Increased costs
  • Management complexity
  • Maintaining currency
  • Vendor dependence
  • Frequent upgrade/replacement cycles
• Metadata is data about data
• Well designed database facilitates data management and generates valuable information
• Poorly designed database leads to bad decision making and organizational failure
• Databases evolved from manual and computerized file systems
• Limitations of file system data management

  • Requires extensive programming
  • System administration is complex and difficult
  • Changing existing structures is difficult
  • Security features are likely inadequate
  • Independent files tend to contain redundant data
  • Structural and data dependency problems
• Database management systems were developed to address file system's inherent weaknesses