Databases

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  • Created by: millard
  • Created on: 25-04-16 17:00
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  • Databases:
    • A persistent and organised store of data
    • DBMS
      • As data can be separated from the application it allows for: more users to access the data, multiple applications can run on the same data and the data structure doesn't depend on the application
      • Principal features of a DBMS:
        • Provide levels of security for different users (controlling who can view what)
        • As data can be separated from the application it allows for: more users to access the data, multiple applications can run on the same data and the data structure doesn't depend on the application
        • Allows multiple users to view the data at once
    • Relational Databases:
      • Modules: like macros, they add functionality to the DB
      • Reports: print-out version of the DB that summaries + presents data
      • Unique Identifiers
        • They are Primary keys which are used to connect the tables
        • Become foreign keys when they are referenced in other Tables
        • By splitting data into different tables you reduce data redundancy
    • Validation
      • Checks that the data is reasonable, sensible and complete BUT NOT ACCURACY
        • Verification is needed to check that the data is as accurate to the source document as possible
          • Enter the data twice
          • Checking the data on the screen against the original document
          • Printout the document and check it against the source document
      • Check digit: Checks that a range of numbers have been entered in the correct order
      • Lookup: DROP DOWN MENU
    • DBMS MUST be able to: Create, Retrieve, Update, Delete
      • DBMS
        • Principal features of a DBMS:
          • Provide levels of security for different users (controlling who can view what)
          • Allows multiple users to view the data at once

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