User:NemoNF/sandbox

EVM 19:37, 12 November 2018 (UTC) This entry refers to Wikipedia Page "Database normalization". 1) There is no sense mentioning Non-first normal form: NORMALIZATION refers to a relational database that has not periodic group or multiple fields. 2) The authorized source is Codd: Codd, E. F. (1971). "Further Normalization of the Data Base Relational Model" (IBM Research Report RJ909 1971), Randall J. Rustin ed., Data Base Systems: Courant Computer Science Symposium 6th, Prentice-Hall, NJ, 1972. and Codd, E. F. (1971a). "Normalized data base structure: a brief tutorial" (IBM R. Report RJ935 1971), Proc. ACM SIGFIDET Workshop, ACM New York ed., New York NY. 3) Codd found three design problems at its "NORMAL FORM" of 1970: (1) Insert anomaly; (2) Delete anomaly; and (3) Update anomaly. All three defects clearly related to two types of defective relational design: (A) PARTIAL DEPENDENCE and (B) TRANSITIVE DEPENDENCE. 4)Partial dependence definition (Being x the primary key of R, some nonkey attribute z of R depends on a subset y₁ of a candidate key y). 5)Transitive dependence definition (Being x the primary key of R, some nonkey attribute z depends —as usual on x and— on another disjoint nonkey subset y). 6) The Third normal form is free of both defects and the Second normal form is free of Partial dependence but not of the Transitive dependence. --- 7) Beyond this point, and following the Codd´s METHOD, each new normal form must repair a design defect; the author of such discovery, must find first a new dependence, and then a new normal form that repair it. Unhappily, nobody had mentioned such tandem "NORMAL FORM(design defect)" after 1971. None Normal Form (after the Third normal form) follows the Codd's scientific standards (Sorry, for the authors of our Wikipedia entry; and also for the other mentioned). In my humble opinion, this topic is a classic that is almost closed. Only the topics: (NORMALIZATION versus SQL NULL -aka MAYBE LOGIC-) and (NORMALIZATION versus QUERY PERFORMANCE) are open. In both cases, I bet on the victory of normalization in both cases. Good luck. Salut, les copains!