Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cimshop!davidm From: cimshop!davidm@uunet.UU.NET (David S. Masterson) Newsgroups: comp.databases Subject: Re: ER versus dependency normalization methods. Message-ID: Date: 28 Nov 90 18:39:50 GMT References: <33445@netnews.upenn.edu> Sender: davidm@cimshop.UUCP Distribution: comp Organization: Consilium Inc., Mountain View, California. Lines: 26 In-reply-to: aaron@grad2.cis.upenn.edu's message of 26 Nov 90 19:48:39 GMT X-Posting-Software: GNUS 3.12 [ NNTP-based News Reader for GNU Emacs ] >>>>> On 26 Nov 90 19:48:39 GMT, aaron@grad2.cis.upenn.edu (Aaron Watters) said: Aaron> I've always suspected that the notion of designing a database using Aaron> data dependancies -- ie, the notion that you start with a pile of Aaron> attributes and functional (and/or other) dependencies and proceed to Aaron> slice up the database into this or that normal form -- was somewhat Aaron> silly and artificial. Have you seen the book "Conceptual Schema and Relational Database Design - A Fact Oriented Approach" by G.M. Nijssen and T.A. Halpin. It discusses a cookbook method (known as NIAM) for relational database design beginning by working with real world examples and then step by step transforming them into a list of facts showing the entities involved, roles they play, constraints on entities in roles, types of facts and constraints in diagrammatic form. There is also methodologies for transforming one design into another equivalent, but more manageable form which then can be optimally normalized (the book talks about optimal normalization being the balance between performance needs and reduction of redundancy). Perhaps this method would seem a little less "silly and artificial"? -- ==================================================================== David Masterson Consilium, Inc. (415) 691-6311 640 Clyde Ct. uunet!cimshop!davidm Mtn. View, CA 94043 ==================================================================== "If someone thinks they know what I said, then I didn't say it!"