Databases

HideShow resource information
View mindmap
  • Databases
    • Persistant + organised store of data
    • organisations
      • loyalty card
      • what they are selling
    • entity
      • a real world object about which data is stored
      • corresponds to tables in the database
      • stored in a database
      • name
      • attributes
        • field name
        • what the field contains
        • first_name
    • foreign key
      • links a primary key to another table
      • not unique
      • avoids data redundancy
      • otherwise data has to be changed every time
    • primary key
      • unique identifier
      • no 2 things can have the same
    • query
      • question asked to a database
      • AND
      • OR
      • NOT
    • types
      • electronic
        • excel
        • simms
        • access
      • paper
        • diaries
        • address book
    • levels of view
      • external
        • what the user sees
      • conceptual
        • how tables are linked/ organised
      • physical
        • the code
        • how data is stored on the storage medium
    • flat file
      • single table
      • set up in a spreadsheet
      • most common
      • simple requirements
      • address book
    • heirarchal
      • when more than one table is in a database
    • validation
      • sensible not correct
      • presence check
        • ensures that data has been entered
      • length check
        • no of characters
      • range check
        • acceptable range of values
      • type check
        • type of data
      • format check
        • desired format
        • picture check
        • input mask used
    • DBMS
      • database management systems
      • create, maintain and interrogate a database
      • physical data
      • software
      • allow data sharing
      • allow multiple user access
      • multiple apps to work
      • hold  one copy of data that everyone can access
        • prevents inconsistent updates
      • provides multiple views

Comments

No comments have yet been made

Similar Computing resources:

See all Computing resources »See all Databases resources »