Object-relational (O/R) middleware is frequently used in practice to bridge the semantic gap (the ‘impedance mismatch’) between object-oriented application systems and relational database management systems (RDBMSs). If O/R middleware is employed, the object model needs to be linked to the relational schema. Following the socalled forward engineering approach, the developer is faced with the ch...

Object-relational mapping tools provide a bridge between objectoriented programming languages and relational database systems. Although the concepts of object-relational mapping are well understood, the performance of object retrieval still is a crucial point in using the tools. Prefetching objects is a means to improve the performance, in particular to avoid the socalled n+1 selects problem. T...

Relational database management systems have been widely used over decades. An important research issue is to find hidden structural information in large relational databases. By hidden structural information we mean the information that cannot be easily found using a traditional query language SQL. In this talk, we discuss how to find hidden structural information in a relational database by vi...

Several mapping schemes have recently been proposed to store XML data in relational tables. Relational database systems are readily available and can handle vast amounts of data very efficiently, taking advantage of physical properties that are specific to the relational model, like sortedness or uniqueness. Tables that originate from XML documents, however, carry some further properties that c...

This paper, the first step to connect relational databases with systems consequence (Kent [5]), is concerned with the semantics of relational databases. It aims to to study system consequence in the logical/semantic system of relational databases. The paper, which was inspired by and which extends a recent set of papers on the theory of relational database systems (Spivak [6] [7]), is linked wi...

This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy r...