Database Design and Relational Theory: Normal Forms and All That Jazz

© C. J. Date 2019

C. J. DateDatabase Design and Relational Theoryhttps://doi.org/10.1007/978-1-4842-5540-7_13

13. ETNF, RFNF, SKNF

C. J. Date¹ 

(1)

Healdsburg, California, USA

 

The essential thing in form is to be free in whatever form is used.

—Wallace Stevens: A Note on Poetry (1937)

Other things being equal, we generally want our databases to be as free of redundancy as possible, where by redundancy I mean more specifically—at least as far as the present chapter is concerned—any redundancy that can be removed by taking projections. And of course we use the discipline of further normalization, or just normalization for short, to help us reach that goal. Now, for many years it was believed that a relvar had to be in fifth normal form (5NF, also known ...