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Chapter 12: Databases

Chapter 12: Databases. Introduction to Databases. Like a library, secondary storage is designed to store information End users need to understand How such stored information is organized using data field, records, files and databases The different types of databases and structures

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Chapter 12: Databases

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  1. Chapter 12: Databases

  2. Introduction to Databases • Like a library, secondary storageis designed to store information • End users need to understand • How such stored information is organized using data field, records, files and databases • The different types of databasesand structures • Competent end users need to be able to find information that is stored in databases

  3. Data • Examples of data include • Facts or observations about people, places, things, and events • Audio, music, photographs, and video • Two ways to view data • Physical view • Logical view

  4. Data Organization • Character • Field • Record • File • Table • Database • Key Field • Batch Versus Real-Time Processing

  5. Key Field • Unique identifier also known as primary field • Common examples • Social Security Number • Student Identification Numbers • Employee Identification Numbers • Part Numbers • Inventory Numbers

  6. Batch Processing • Batch processing • Data is collected over a period of time and the processing happens later all at one time

  7. Real-Time Processing • Real-time processing • Also known as online processing because it happens immediately during the transaction

  8. Databases • Collection of integrated data • Logically related files and records • Databases address data redundancyand data integrity • Need for databases • Database management

  9. Need for Databases • Sharing • Security • Avoid Data duplication • Data integrity

  10. Database Management • DBMS engine • Data definitionsubsystem • Data dictionary • Data manipulationsubsystem • Query-by-example • Structured query language (SQL) • Application generation subsystem • Data administration subsystem

  11. DBMS Structure • DBMS programs are designed to work with data that is logically structured or arranged • Data models define rules and standards for data in a database • Five common data models are • Hierarchical database • Network database • Relational database • Multidimensional database • Object-oriented database

  12. Hierarchical Database • Fields or records are structured in nodes • Nodes are points connected like branches • One parent per node; a parent has severalchild nodes (one-to-many relationship) Return

  13. Network Database • Hierarchical node arrangement • Each child node may have more than one parent node (many-to-many relationship) • Additional nodes are called pointers • Nodes can be reached through multiple paths Return

  14. Relational Database • Data stored in table called a relation • Tables consist of rows and columns • Tables related via a common data item Return

  15. Multidimensional Database • A variation and an extension of the relational model to include additional dimensions, sometimes called a data cube • Good for representing complex relationships • Advantages over relational • Conceptualization • Processing speed Return

  16. Object-Oriented Database • Works with unstructured data • Photographs • Audio • Video • Objects contain bothdata and instructions • Organize using objects,classes, entities,attributes, and methods Return

  17. Types of Databases • Individual • Company or shared • Distributed • Commercial

  18. Individual Databases • Also called a microcomputer database • Integrated file collection for one person usually under the person’s direct control • Generally stored on the user’s hard-disk drive or on a LAN file server Return

  19. Company or Shared Databases • Usually stored on a central database server and managed by a database administrator • Users throughout a company can access the database through the company’s networks Return

  20. Distributed Databases • Database is located in a place or places other than where users are located • Typically, database servers on a client/server network provide the link between users and the distant data Return

  21. Commercial Databases • Generally an enormous database developed by an organization to cover particular subjects • Access is offered to thepublicor selected outside individualsfor a fee • Most commercial databases are designed for organizational and individual use • Also referred to as information utilities or data banks Return

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