BCNF: superkey or candidate key ?

From: <masong_at_sbcglobal.net>
Date: Thu, 21 Sep 2006 11:33:33 GMT
Message-ID: <1158838496_4271_at_sp6iad.superfeed.net>



C.J. Date in a recent text defines BCNF in terms of superkey. ... every nontrivial FD A -> B satisfied by R, A is a superkey for R.

Previously he (and others) defined it where A had to be a candidate key (which is irreducible).

The two are not equivalent. The prior definition was more strict. What is the accepted definition du jour ? And what motivated the change ?

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