ping@latcs1.oz (Ping Li) (09/19/89)
Wondering if there are any tools available that 1) construct a relational data model; 2) and such a model should be either a 4th NORMAL FORM or a 3rd NORMAL FORM. Thank you in advance.
UH2@PSUVM.BITNET (Lee Sailer) (09/20/89)
In article <6403@latcs1.oz>, ping@latcs1.oz (Ping Li) says: > > Wondering if there are any tools available that > > 1) construct a relational data model; > > 2) and such a model should be either a 4th NORMAL FORM > or a 3rd NORMAL FORM. > > > Thank you in advance. Good question. There are tools that *help* you build a normalized set of relations. For someone who has normalized many, many relations, it is hard to avoid building normalized relations by instinct. By "tools" I mean CASE modeling tools such as Excelerator, the Iconix stuff, and SilverRun LDM and ERM. Also, IDE for Unix. But, it sounds like you want something that will do the actual normalization. There are algorithms for this (See Ullman, again) but I cannot recommend them. 1. You still must determine all of the functional dependencies by hand. The FD's are *business policy*, not computer technology. 2. They are computationally burdensome. 3. They sometimes find counter-intuitive relations. 4. The user/analyst/developer loses a great opportunity to become really familiar with the contents of the database.