INTRODUCTION

• Database


  Specialized structure that allows computer-based systems to store, manage, and retrieve data very quickly
• Databases are valuable assets for decision making
• Database design


  • Defines the database's expected use
  • Different approach needed for different types of databases
  • Avoids redundant data
  • Poorly designed database generates errors that can lead to bad decisions and failure of organization
• Database design is the process that yields the description of the database structure and determines the database components
• Managing data with file systems is obsolete
• Understanding file system characteristics makes database design easier to understand
• Awareness of problems with file systems is important
• Data

  Raw facts and figures that do not have any meaning until processed and given a context
• Information


  Data which has been processed within a context in order to give it meaning
• Knowledge


  Familiarity, awareness, and understanding of information as it applies to an environment
• Examples of knowledge


  • Teacher applying a rule to discuss low scores with students
  • Shop manager ordering more of the most popular ice cream flavor
  • Holiday cottage owner lowering rental price to get more bookings
• DBMS (Database Management System)


  Collection of programs that manages database structure and controls access to data
• Role of the 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
• Advantages of the DBMS

  • Better data integration and less data inconsistency
  • Increased end-user productivity
  • Improved data sharing, security, access, decision making, and data quality
• Types of databases by number of users

  • Single-user database
  • Multiuser database
  • Workgroup database
  • Enterprise database
• Types of databases by location

  • Centralized database
  • Distributed database
  • Cloud database
• Types of databases by use

  • Transactional (or production) database
  • Data warehouse
• A poorly designed database generates errors that can lead to bad decisions and failure of an organization
• The evolution of data processing has progressed from manual file systems to computerized file systems to modern end-user productivity tools like spreadsheets
• Database design


  The process that yields the description of the database structure and determines the database components
• Example of a poor design


  • It would be difficult, if not impossible, to produce an alphabetical listing of employees based on their last names
• File System Data Processing

  Evolution from manual file systems to computerized file systems to database systems
• Manual File Systems


  • Accomplished through a system of file folders and filing cabinets
  • Organization within folders based on data's expected use (ideally logically related)
  • Adequate for small amounts of data with few reporting requirements
  • Finding and using data in growing collections of file folders became time-consuming and cumbersome
• Computerized File Systems


  • Generating reports from manual file systems was slow and cumbersome
  • Data processing (DP) specialist hired to create a computer-based system that would track data and produce required reports
  • Initially, computer files were similar in design to manual files
• Structural dependence


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


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


  Changes in the data storage characteristics without affecting the application program's ability to access the data
• Logical data format


  How the human being views the data
• Physical data format


  How the computer "sees" the data
• Field definitions and naming conventions

  Flexible record definition anticipates reporting requirements by breaking up fields into their component parts
• Data redundancy


  Exists when the same data are stored unnecessarily at different places
• Types of data anomalies

  • Update anomalies
  • Insertion anomalies
  • Deletion anomalies
• Database system


  An organization of components that define and regulate the collection, storage, management and use of data within a database environment
• Parts of a database system environment

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

  • Systems administrators
  • Database administrators (DBAs)
  • Database designers
  • Systems analysts and programmers
  • End users
• DBMS functions

  • Data dictionary management
  • Data storage management
  • 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
• Data independence and efficient access
• Reduced application development time
• Data integrity and security
• Uniform data administration