Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!postnews.google.com!i42g2000cwa.googlegroups.com!not-for-mail From: "-CELKO-" Newsgroups: comp.databases.theory Subject: Re: Who first (publicly) asserted 3NF is "good enough"? Date: 18 Sep 2006 14:55:36 -0700 Organization: http://groups.google.com Lines: 17 Message-ID: <1158616536.275793.73440@i42g2000cwa.googlegroups.com> References: NNTP-Posting-Host: 63.246.191.202 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1158616541 22689 127.0.0.1 (18 Sep 2006 21:55:41 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Mon, 18 Sep 2006 21:55:41 +0000 (UTC) In-Reply-To: User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.7) Gecko/20060909 Firefox/1.5.0.7,gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: i42g2000cwa.googlegroups.com; posting-host=63.246.191.202; posting-account=EzrcbQ0AAACimcwOd0QEJhKx5W98nxwt Xref: dp-news.maxwell.syr.edu comp.databases.theory:45013 >> .. one so frequently sees books and articles in which it is asserted that 3NF is "good enough" .. does anyone know if there was a single authoritative writer (long ago) who expressed this foolish idea? << I am not sure the source of the myth, I have a feeling it goes back to the early forms of ER diagrams which did not have much in the way of showing compound keys or "tricky" relationships. A lot of the early ER tools could only go to 3NF, so maybe that was where it started. And, as Bob pointed out, for a lot of commercial apps, there is an industry standard or internally defined key that you have to use (UPC, EAN, VIN, ISBN, etc.), so most of the tables have a simple key. Also, if a table is all key, then it is in 5NF. When I have to teach a class, I pull out a (buyer, seller, lender) table that demonstrates JPNF problems and a (classroom,course, teacher, period) table where any three columns are a key for overlapping UNIQUE constraints.