NORMALISATION

NORMALISATION

1. 1NF

   • All data is atomic
   • Has a PK
   • No repeating data/fields
   • unique field names

2. 2NF

   • Already in 1NF
   • All non-key fields are dependent on the whole PK
     • all field data can be found by looking at entire PK

3. 3NF

   • table is already in 2NF
   • No functional dependency between non-key fields

4. ADVANTAGES

   • increased data integrity - only 1 copy so correct
   • flexibility for expanding database in future
   • easier to maintain database
   • less storage space needed, so smaller hard drive

5. DISADVANTAGES

   • reduces database performance - more tables=slower processing
   • results of historial calculations can't be stored
   • may not meet needs of comapny, e.g. store address as 1 field