DBMS 1

• Database 


  an organized collection of logically related data
• data


  a stored representation of meaningful objects and events
• structured data: number, text, dates
• unstructured data: images, videos, documents
• Information


  data processed to increase knowledge in the person using the data
• metadata


  data that describes the properties and context of user data
• Disadvantages of File Processing

  • Program-data dependence
  • Duplication of data
  • Limited data sharing
  • Lengthy Development Times
  • Excessive Program Maintenance
• Problems with Data Dependency

  • Each application programmer must maintain his/her own data
  • Each application program needs to include code for each file's metadata
  • Each application program must have its own processing routines for reading, inserting, updating, and deleting data
  • Lack of coordination and central control
  • Non-standard file formats
• Problems with Data Redundancy

  • Waste of space to have duplicate data
  • Causes more maintenance headaches
  • Biggest problem: Data changes in one file could cause inconsistencies, compromises in data integrity
• The database approach is a software system that is used to create, maintain, and provide controlled access to user databases
• Database Management System manages data resources like an operating system manages hardware resources
• data models


  graphical diagram capturing the nature and relationship of data
• enterprise data model


  high-level entities and relationships for the organization
• entities


  noun form describing a person, place, object, event, or concept
• relationships


  it is between entities; usually one-to-many (1:M). many-to-many (M:N), but could also be one-to-one (1:1)
• relational database


  database technology involving tables (relations) representing entities and primary/foreign keys representing relationships
• Advantages of the Database Approach

  • Program-data independence
  • Planned data redundancy
  • Improved data consistency
  • Improved data sharing
  • Increased application development productivity
  • Enforcement of standards
  • Improved data quality, accessibility, and responsiveness
  • Reduced program maintenance
  • Improved decision support
• data modeling and design tools


  automated tools used to design databases and application programs
• repository


  a centralized storehouse of metadata
• Database Management System


  software for managing the database
• database


  a storehouse of the data
• application programs


  software using the data
• user interface


  text, graphical displays, menus, etc. for the user
• data/database administrators


  personnel responsible for maintaining the database
• system developers


  personnel responsible for designing the database and software
• end users


  people who use the applications and database
• Enterprise Data Model

  • First step in the database development process.
  • Specifies scope and general content.
  • Overall picture of organizational data at a high level of abstraction.
  • Entity-relationship diagram.
  • Descriptions of entity types.
  • Relationship between entities.
  • Business rules.
• System Development Life Cycle


  detailed, well planned development process; time-consuming, but comprehensive; long development cycle
• prototyping

  • Rapid application development (RAD)
  • Cursory attempt at conceptual data modeling
  • Define the database during the development of the initial prototype
  • Repeat implementation and maintenance activities with new prototype versions
• System Development Life Cycle

  • Planning
  • Analysis
  • Logical Design
  • Physical Design
  • Implementation
  • Maintenance
• Planning

  Purpose: Preliminary understanding

  Deliverable: Request for study

  Database Activity: enterprise modeling and conceptual data modeling
• Analysis

  Purpose: Thorough requirements analysis and structuring

  Deliverable: Functional system specifications

  Database activity: Thorough and integrated conceptual data modeling
• Logical Design

  Purpose: Information requirements elicitation and structure

  Deliverable: Detailed design specification

  Database Activity: Logical database design
• Physical design

  Purpose: develop technology and organizational specifications

  Deliverable: Program/data structures, technology purchases, organizational redesigns

  Database Activity: Physical database design (Define database to DBMS, physical data organization database processing programs)
• Implementation

  Purpose: Programming, testing, training, installation, documenting

  Deliverable: Operational program documentation, training materials

  Database Activity: database implementation, including coded programs, documentation, installation, and conversion
• Maintenance

  Purpose: Monitor, repair, and enhance

  Deliverable: Periodic audits

  Database Activity: data maintenance, performance analysis and tuning, error corrections
• project


  a planned undertaking of related activities to reach an objective with a beginning and an end