chapter 1 comp

• Data


  A collection of facts, figures and statistics related to an object, that can be processed to produce meaningful information
• Information


  The manipulated and processed data, e.g. the percentage of student results
• Operations


  1. Manipulation of data (after capturing from different sources) to achieve required objectives and results

  2. Data Capturing: Data must be recorded or captured in some form before it can be processed

  3. Data Manipulation: Classifying, Calculations, Sorting, Summarizing
• Managing the Output Results

  1. Storing and Retrieval: Data is retained for future reference .fetching the stored data or information is called retrieving

  2. Communication and Reproduction: Data may be transferred from one location or operation to another, for further processing. it is sometimes necessary to copy or to make duplicate of data. this activity is called reproduction.
• Record


  A collection of related fields (facts about something) treated as a single unit
• File


  A collection of related records treated as a single unit
• File Types (Usage point of view)

  • Master File
  • Transaction File
  • Backup File
• File Types (Functional point of view)

  • Program files
  • Data files: .doc, .rtf, .xls, .wks, .dat, .dbf, .mdb, .txt, .tif, .jpg, .eps, .gif, .bmp, .wav, .mid, .avi, .mpg
• File Organization (Storage point of view)

  • Sequential Files
  • Direct or Random Files
  • Indexed Sequential
• Database


  A collection of logically related data sets or files, organized in various ways to meet processing and retrieval requirements
• Database System


  • Involves four major components: Data, Hardware, Software, Personnel
• Database Objectives


  • Data Integration: Information is coordinated from different files and operated on a single file
  • Data Integrity: Only one copy of data is kept, therefore data is more consistent
  • Data Interdependence: Organization of data can be changed without re-programming
• Types of Database Models

  • Hierarchical Model
  • Network Model
  • Relational Model
• Database Management System (DBMS)

  A collection of programs used for storing and manipulating databases, an improvement over traditional file management systems
• Objectives of Database Management System

  • Shareability: Different people and processes can use the same actual data
  • Accessibility: Data can be accessed by authorized users
  • Integrity: Data is accurate, consistent and up-to-date
  • Security: Unauthorized access to data is prevented
  • Reduced Redundancy: Duplication of data is almost impossible
  • Improved Productivity: Faster processing and retrieval of data
• Entities


  Possess interrelationships depicted by a network-like diagram, based on data content not pointer chains or structural connections
• The data management system (a collection of programs) which is used for storing and manipulating databases is called database management system (DBMS)
• DBMS is an improvement over traditional file management systems, using DBMS software (database manager) to control the overall structure of a database and access to the data itself
• DBMS is normally used for large or medium sized organizations, having heterogeneous types of files, used for different purposes
• In DBMS, data elements are so integrated, cross referenced and shared that duplication of data is almost impossible
• Objectives of Database Management System

  • Shareability
  • Availability
  • Evolvability
  • Database Integrity
• Data Independence


  Application programs are not aware of the physical implementation of the data sets, DBMS sits between application programs and the actual data sets
• Database Systems


  • Support complex data relationships
  • Provide sophisticated data security features
  • Provide backup/recovery mechanism
• Advanced capabilities of DBMS include on-line and ad-hoc reporting capabilities, data independence, complex data structures, data security, and backup/recovery
• Disadvantages of Database Systems

  • Require additional system overhead
  • Additional training required for staff
  • Problems can multiply in selecting wrong database environment
  • Data must be considered a corporate resource
  • Need for a data dictionary
• Features of a DBMS

  • Data Dictionary
  • Utilities
  • Query Language
  • Report Generator
  • Access Security
  • Backup and Recovery
• SQL (Structured Query Language) is normally used for creating table structures, entering data, and retrieving/updating records in databases
• A report generator is a program used to produce on-screen or printed documents from the database
• Database administrators can assign specific access privileges for users of the databases using the access security feature
• Backup and recovery feature allows backup of data and reinstatement in case of data failure, corruption or loss