E.F. Codd, Normalized database structure: a brief tutorial, in: ACM SIG-FIDET Workshop on Data Description, Access, and Control, San Diego, California, November, 1971.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....2.2. The nested structure of this relation resembles the XML hierarchical structure. 2. 2 Normal Forms for Non First Normal Form Relations Makinouchi [MAK 77] was the first one to say that a nested relation can be normalized in order to avoid update anomalies, just as in Codd s third normal form [COD 71, COD 74] However, it is not necessary that this relation be in the first normal form. According to [MAK 77] there are two alternatives to remove redundancy from a relation: to decompose the relation considering the 1NF, 2NF, 3NF and so on, or to nest the relation, putting it in Normal Form. ....

CODD, E. F. Normalized data base structure: a brief tutorial. In: ACMSIGFIDET,

....any grouping of domains can be considered to be a relation. To avoid undesirable properties in maintaining relations, a normalization process is proposed to transform arbitrary relations into the first normal form, then into the second normal form, and finally into the third normal form (3NF) [ 9, 11]. We shall show that the entity and relationship relations in the entity relationship model are similar to 3NF relations but with clearer semantics and without using the transformation operation. Let us use a simplified version of an example of normalization described in [9] The following three ....

....normal form (3NF) 9, 11] We shall show that the entity and relationship relations in the entity relationship model are similar to 3NF relations but with clearer semantics and without using the transformation operation. Let us use a simplified version of an example of normalization described in [9]. The following three relations are in first normal form (that is, there is no domain whose elements are themselves relations) EMPLOYEE (EMPLOYEE NO) PART (PART NO, PART DESCRIPTION, QUANTITY ON HAND) PART PROJECT (PART NO, PROJECT NO, PROJECT DESCRIPTION, PROJECT MANAGER NO, ....

CODD, E.F. Normalized data base structure: A brief tutorial. Proc. ACM-SIGFIDET

....the relation r into: r 2 = Pi XY (r) r 1 = Pi XZ (r) 3) then, the natural join of both projections recovers exactly the original relation r itself, i.e, it is a loss less decomposition: r = r 1 . r 2 (4) This is the idea behind the process of normalization of a relational database (see [7, 8, 27]) and we want to extend it to the fuzzy case. Now, we proceed to introduce some basic concepts regarding the fuzzy extension of relational databases. 1.2 Fuzzy Relational Databases We consider a general definition of Fuzzy Relational Database where a relation r is a subset of r Theta n i=1 ....

E.F. Codd. Normalized data base structure: A brief tutorial. In ACM SIGFIDET Workshop on Data Description, Access, and Control. San Diego, 1971.

....= Pi XZ (r) r 2 = Pi XY (r) 2) then, the natural join of both projections recovers exactly the same original relation r, i.e, it is a loss less decomposition: r = r 1 . r 2 (3) It is pointed that, in order to avoid the problems of redundancy and updating, this process of normalization (see [5, 6, 26]) is done by the database manager before introducing data into a relational scheme. Nevertheless, if the desing was not correct, and a functional dependency exists, then equation 3 assures that we can replace r by its projections r 1 and r 2 , isolating the information conveyed by the dependency ....

E.F. Codd. Normalized data base structure: A brief tutorial. In ACM SIGFIDET Workshop on Data Description, Access, and Control. San Diego, 1971.

....the relation r into: r 1 = Pi XZ (r) r 2 = Pi XY (r) 2) then, the natural join of both projections recovers exactly the original relation r itself, i.e, it is a loss less decomposition: r = r 1 . r 2 (3) This is the idea behind the process of normalization of a relational database (see [4, 5, 22]) and we want to extend it to the case of fuzzy databases. 1.2 Fuzzy Relational Databases We consider a general definition of Fuzzy Relational Database where a relation r in such a database is a subset of the following cartesian product: r Theta n i=1 P (D i ) where D i is a crisp ....

E.F. Codd. Normalized data base structure: A brief tutorial. In ACM SIGFIDET Workshop on Data Description, Access, and Control. San Diego, 1971.

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E.F. Codd, Normalized database structure: a brief tutorial, in: ACM SIG-FIDET Workshop on Data Description, Access, and Control, San Diego, California, November, 1971.

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