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The normalisation process is often described in terms of stages known as first, second,
third, fourth and fifth normal forms (1NF–5NF). Although we have not adopted this
approach in the present text, the terminology is sufficiently prevalent in the literature to
warrant a brief explanation. The general idea is that at each successive stage of
normalisation certain undesirable features are eliminated from the initial
unnormalised table. First normal form is obtained by eliminating repeating groups,
second normal form is obtained by eliminating non-identifier attributes that are not
functionally dependent on the whole of the identifier, and ...