1970 E.F.Codd introduces 1st Normal Form (1NF) 1971 E.F.Codd introduces 2nd and 3rd Normal Form (2NF, 3NF) 1974 Codd & Boyce define Boyce/Codd Normal Form (BCNF) 2002 Date, Darween, Lorentzos define 6th Normal Form (6NF) Goals: Avoid anomalies when inserting, updating or deleting Minimize redesign when extending the schema Make the model informative to users Avoid bias towards a particular style of query