A Solution to the Hidden Key Problem of 3NF Relational Schemata

摘要

Two approaches to conceptual relational data base design are reviewed and techniques for transforming a third normal form (3NF) relational schema into a representation suited to the target data base management system (DBMS) are developed. A relation in a 3NF schema may have not only a number of candidate keys, but in general also a number of hidden keys, corresponding to hidden functional dependencies spanned by the relation. A solution to this problem is proposed, using an approach that involves joins of relations in the 3NF schema.