chapter 1

• Data


  Raw facts
• Information

  Have not yet been processed to reveal their meaning to the end user
• Data

  • Building blocks of information
  • Generation, storage, and retrieval of data
• Information

  • Produced by processing raw data to reveal its meaning
  • Requires context
  • Should be accurate, relevant, and timely to enable good decision making
• Database

  Shared, integrated computer structure that stores a collection of end-user data and metadata
• Metadata

  Data about data, which the end-user data are integrated and managed
• Database management system (DBMS)


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


  • Intermediary between the user and the database
  • Enables data to be shared
  • Presents the end user with an integrated view of the data
  • Receives and translates application requests into operations required to fulfill the requests
  • Hides database's internal complexity from the application programs and users
• Types of Databases


  • Single-user database
  • Multiuser database
  • Centralized database
  • Distributed database
  • Cloud database
  • General-purpose databases
  • Discipline-specific databases
  • Operational database
  • Analytical database
  • Data warehouse
  • Online analytical processing (OLAP)
  • Business intelligence
• Single-user database


  • Supports one user at a time
• Multiuser database

  • Supports multiple users at the same time
• Centralized database


  • Data is located at a single site
• Distributed database


  • Data is distributed across different sites
• Cloud database


  • Created and maintained using cloud data services that provide defined performance measures for the database
• General-purpose databases

  • Contains a wide variety of data used in multiple disciplines
• Discipline-specific databases


  • Contains data focused on specific subject areas
• Operational database


  • Designed to support a company's day-to-day operations
• Analytical database


  • Stores historical data and business metrics used exclusively for tactical or strategic decision making
• Data warehouse

  • Stores data in a format optimized for decision support
• Online analytical processing (OLAP)

  • Tools for retrieving, processing, and modeling data from the data warehouse
• Business intelligence

  • Captures and processes business data to generate information that support decision making
• Types of Data

  • Unstructured data
  • Structured data
  • Semistructured data
• Unstructured data

  It exists in their original state
• Structured data

  It results from formatting, structure is applied based on type of processing to be performed
• Semistructured data

  Processed to some extent
• Extensible Markup Language (XML)

  Represents data elements in textual format
• Database Design

  • Focuses on the design of the database structure that will be used to store and manage end-user data
  • Well-designed database facilitates data management and generates accurate and valuable information
  • Poorly designed database causes difficult-to-trace errors
• The Wealth of Nations was written in 1776
• Basic File Terminology

  • File
  • Record
  • Field
  • Data item
• Problems with File System Data Processing
• Structural dependence

  Access to a file is dependent on its own structure, all file system programs are modified to conform to a new file structure
• Structural independence

  File structure is changed without affecting the application's ability to access the data
• Data dependence

  Data access changes when data storage characteristics change
• Data independence

  Data storage characteristics is changed without affecting the program's ability to access the data
• Data redundancy


  Unnecessarily storing same data at different places
• Islands of information

  • Scattered data locations, increases the probability of having different versions of the same data
• Types of Data Anomaly

  • Update anomaly
  • Insertion anomaly
  • Deletion anomaly
• Database Systems


  • Logically related data stored in a single logical data repository, physically distributed among multiple storage facilities
  • DBMS eliminates most of file system's problems
  • Current generation DBMS software stores data structures, relationships between structures, and access paths, defines, stores, and manages all access paths and components
• DBMS Functions
• Data dictionary


  Stores definitions of the data elements and their relationships