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NORMALISATION

Description

A level A Level ICT Mind Map on NORMALISATION, created by Fiona Faulkner on 14/05/2013.
Fiona Faulkner
Mind Map by Fiona Faulkner, updated more than 1 year ago
Fiona Faulkner
Created by Fiona Faulkner about 12 years ago
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Resource summary

NORMALISATION
  1. 1NF
    1. All data is atomic
      1. Has a PK
        1. No repeating data/fields
          1. unique field names
          2. 2NF
            1. Already in 1NF
              1. All non-key fields are dependent on the whole PK
                1. all field data can be found by looking at entire PK
              2. 3NF
                1. table is already in 2NF
                  1. No functional dependency between non-key fields
                  2. ADVANTAGES
                    1. increased data integrity - only 1 copy so correct
                      1. flexibility for expanding database in future
                        1. easier to maintain database
                          1. less storage space needed, so smaller hard drive
                          2. DISADVANTAGES
                            1. reduces database performance - more tables=slower processing
                              1. results of historial calculations can't be stored
                                1. may not meet needs of comapny, e.g. store address as 1 field
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