4.3.6 - Database Systems - Database Systems

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  • Created by: Annie
  • Created on: 05-05-13 20:18
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  • Database Systems
    • Data security
      • In a flat file database, the entire file will have the same (or no) security
      • A relational database can have different security levels on each of the tables
        • Different groups of users can have rights based upon read/write/add permissions
        • Employers can view/amend data relevant to their job role
      • Such groups will often be based upon a hierarchy with managers having fuller access than lower level employees
    • Data warehousing
      • Data is used to support organisational decision making
      • Data is available for analysis
      • Enables predictions of future sales to be much more accurate
        • Comparisons between regional sales of different products
      • Examples would include customer transaction details
        • For banks and supermarkets
      • Data is non-volatile and time invariant
        • Doesn't change
      • The idea that data for an organisation is stored in a central location
        • Large organisations have huge amounts of data - hence the term warehouse
    • Data mining
      • Using data stored to extract useful information
      • It is a speculative process and investigates potential patterns
      • There is the presumption that dormant within the data are undiscovered patterns, groupings, sequences or associations
      • Software uses complex algorithms
      • Data of value can be processed into a report to help decision making
    • Flat file database
      • One or  more tables with no relation between them
    • Database management system (DBMS)
      • A DBMS is used to manage the data held in the database and provide an effective connection to other applications which use data
        • Data to be queried and searched
        • New data to be added to tables
        • Updates to be made to large datasets
        • Security of the data to be maintained
        • Data exchange with other applications
          • Applications and the DBMS can be updated independently of each other
        • Referential integrity, validation (etc.) are used to maintain the integrity of the data
      • Microsoft Access is a Database Management System
        • Difference between MIS: Different Information outputs such as graphs, charts etc. for decision making purposes
    • Query Languages (SQL)
      • Standard query language is used to flexibly search all databases
      • Access includes a graphical query interface that makes it easier for users to search a database
        • Knowing SQL means much more intricate searches can be created - ideal for data mining
    • Distributed  Databases
      • Large organisations frequently store data in a range of locations, typically based upon where the data is being used or accessed most
        • To maintain a high speed response!
      • A distributed database allows the user to access the data as if it is in one location
        • Access speeds may be slower if some/all the searched data is located in different locations
      • Data is controlled under the control of a single DBMS
      • A customer looking for a certain item may go into a shop -
        • The  employee can search within the store database
        • If no findings, can search other store databases so the customer can find it
      • Advantages
        • All data in an organisation can be accessible through a single DBMS
        • Complex data mining is possible from a single query
      • Disadvantages
        • Complex and costly to set up
        • Increased security risks
        • System relies upon communication links
          • If these fail, so does the system
        • Various differences at each shop effecting communication
          • e.g. Road works hitting a cable
    • Data Dictionary
      • Vital piece of database development documentation
      • It provides details of the design should the database have to be upgraded in the future
        • Makes updates easier without disrupting company operations more than necessary
      • Useful if original database designers are no longer around
      • Shows data
        • Validation Used
        • Field lengths
        • Relationships
        • Data types
        • Key fields
        • Field names

Comments

Mr A Gibson

Another really useful Mind Map from this contributor (see here for the complete list). Print off on A3, learn and use the "Test Yourself" feature to review what you have understood. WJEC specific but good for all specifications that have databases included.

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