Normalisation - Second normal form

• Applicable when: A table has a compound key (two or more key fields).
• Method: Remove partial dependencies. For records whose keys have more than one data item (compound keys), ensure that all other items are dependent on the whole key (functionally dependent). Split records if necessary to achieve this (second normal form).

Example:

• Notes:
  • SupplierName is functionally dependent on SupplierId
  • SuppDetails is functionally dependent on SupplierId
  • PartPrice is functionally dependant on both PartId AND  SupplierId
  • eg. X-U1 can be supplied by two suppliers.

Step 1: Split into separate tables (projection)

[Rev 16/05/99] 13/6/97  © 1997-99 V/2-Com (Verhaart), P O Box 8415, Havelock North, New Zealand.