Some problems related to keys and the Boyce-Codd normal form

The aim of this paper is to investigate the connections between minimal keys and antikeys for special Sperner-systems by hypergraphs. The Boyce-Codd normal form and some related problems are also studied in this paper

Ensuring the existence of a BCNF-decomposition that preserves functional dependencies in O (N2) time

A simple condition is presented that ensures that a relation scheme R with a set F of functional dependencies has a Boyce-Codd normal form (BCNF)-decomposition that has the lossless-join property and preserves functional dependencies

Normalizing Relations: One-to-One Relationships

This paper discusses problems and confusion that can arise in normalizing certain relations, using the commonly accepted practices of identifying primary keys and defining normal forms. Specifically, normalization of relations that combines information on two different entities with a one-to-one relationship is discussed. It is shown that for such relations, using the standard normalization procedures may lead to the conclusion that a relation in Boyce-Codd normal form (BCNF) still suffers from insertion and deletion anomalies. Methods to deal with such cases are presented

Justification for inclusion dependency normal form

Functional dependencies (FDs) and inclusion dependencies (INDs) are the most fundamental integrity constraints that arise in practice in relational databases. In this paper, we address the issue of normalization in the presence of FDs and INDs and, in particular, the semantic justification for Inclusion Dependency Normal Form (IDNF), a normal form which combines Boyce-Codd normal form with the restriction on the INDs that they be noncircular and key-based. We motivate and formalize three goals of database design in the presence of FDs and INDs: noninteraction between FDs and INDs, elimination of redundancy and update anomalies, and preservation of entity integrity. We show that, as for FDs, in the presence of INDs being free of redundancy is equivalent to being free of update anomalies. Then, for each of these properties, we derive equivalent syntactic conditions on the database design. Individually, each of these syntactic conditions is weaker than IDNF and the restriction that an FD not be embedded in the righthand side of an IND is common to three of the conditions. However, we also show that, for these three goals of database design to be satisfied simultaneously, IDNF is both a necessary and sufficient condition

Diseño de bases de datos relacionales con DBDStudio

En este artículo se presenta DBDStudio, una herramienta software implementada en formato aplicación web. El objetivo de la misma es la de asistir en el análisis y diseño de bases de datos relacionales que utilicen condiciones de integridad de tipo dependencia funcional. Entre otras, la aplicación permite calcular las claves, el cierre de un conjunto de atributos, el recubrimiento minimal, detectar y normalizar hasta las formas normales de 3FN (tercera forma norma) y FNBC (forma normal de Boyce y Codd). Pensamos que la herramienta puede resultar valiosa para las personas relacionadas con el proceso de enseñanza/aprendizaje del diseño de bases de datos relacionales, facilitándoles a los estudiantes la comprensión de las principales nociones teóricas gracias a los diversos algoritmos implementados.In this paper we present DBDStudio, a software tool, developed as a web-app. The goal is to assist in the analysis and design of relational databases based on functional dependencies. Among others, the app allows to compute keys, closure of attribute sets, minimal cover, detect and normalize till 3NF (third normal form) and BCNF (Boyce and Codd normal form). We think this tool is valuable as a teaching resource for who are involved in the training of relational database design. The tool provides great help for the students, making easier learning the theoretical notions thanks to the different implemented algorithms

Clarifying Normalization

Confusion exists among database textbooks as to the goal of normalization as well as to which normal form a designer should aspire. This article discusses such discrepancies with the intention of simplifying normalization for both teacher and student. This author’s industry and classroom experiences indicate such simplification yields quicker learning and more complete understanding by students

Strong types for relational databases: functional pearl

Haskell's type system with multi-parameter constructor classes and functional dependencies allows static (compile-time) computations to be expressed by logic programming on the level of types. This emergent capability has been exploited for instance to model arbitrary-length tuples (heterogeneous lists), extensible records, functions with variable length argument lists, and (homogenous) lists of statically fixed length (vectors).We explain how type-level programming can be exploited to define a strongly-typed model of relational databases and operations on them. In particular, we present a strongly typed embedding of a significant subset of SQL in Haskell. In this model, meta-data is represented by type-level entities that guard the semantic correctness of database operations at compile time.Apart from the standard relational database operations, such as selection and join, we model functional dependencies (among table attributes), normal forms, and operations for database transformation. We show how functional dependency information can be represented at the type level, and can be transported through operations. This means that type inference statically computes functional dependencies on the result from those on the arguments.Our model shows that Haskell can be used to design and prototype typed languages for designing, programming, and transforming relational databasesFundação para a Ciência e a Tecnologia (FCT) - POSI/ICHS/44304/2002; SFRH/BPD/11609/2002