Translating Advanced Integrity Checking Technology to SQL

The main goal of this chapter is to arrive at a coherent technology for deriving efficient SQL triggers from declarative specifications of arbitrary integrity constraints. The user may specify integrity constraints declaratively as closed queries in predicate calculus syntax (i.e., sentences in the language of first-order logic, abbr. FOL), as datalog denials, as query conditions in SQL WHERE clauses, or in some other, possibly more user-friendly manner (e.g., via a dialog-driven graphical or natural language interface which internally translates to equivalent WHERE clause conditions). As we are going to see, the triggers derived from such specifications behave such that whenever some update event would violate any of the integrity constraints, one or several of the triggers derived from that constraint are activated in order to enforce the constraint. That is, the violation is either prevented by rolling back the update or repaired instantly by subsequent further updates.

Preserving Relationship Cardinality Constraints in Relational Schemata

This chapter is devoted to the study of the transformation of conceptual into logical schemata in a methodological framework focusing on a special ER construct: the relationship and its associated cardinality constraints. The section entitled “EER Model Revised: relationships and cardinality constraint” reviews the relationship and cardinality constraint constructs through different methodological approaches to establish the cardinality constraint definition that will be followed in next sections. The section “Transformation of EER Schemata into Relational Schemata” is related to the transformation of conceptual n-ary relationships (n³2) into the relational model following an active rules approach. Finally, several practical implications as well as future research paths are presented.

Integrity Issues in the Web

Issues related to integrity in databases and distributed databases have been introduced in previous chapters. Therefore, the integrity problem in databases and how it can be managed in several data models (relational, active, temporal, geographical, and object-relational databases) are well known to the reader. The focus of this chapter is on introducing a new paradigm: The Web as the database, and its implications regarding integrity, i.e., the progressive adaptation of database techniques to Web usage. We consider that this will be done in a quite similar way to the evolution from integrated file management systems to database management systems.

Integrity Constraints in an Active Database Environment

This chapter surveys the interaction between active rules and integrity constraints. First, we analyze the static case following the SQL-1999 Standard Committee point of view which, up to date, represents the state of the art. Then, we consider the case of dynamic constraints for which we use a temporal logic formalism. Finally, we discuss the applicability, limitations and partial solutions found when attempting to ensure the satisfaction of dynamic constraints.

Integrity Constraints in Spatial Databases

This chapter addresses the relationship that exists between the nature of spatial information, spatial relationships, and spatial integrity constraints, and proposes the use of OMT-G (Borges et al., 1999; Borges et al., 2001), an object-oriented data model for geographic applications, at an early stage in the specification of integrity constraints in spatial databases. OMT-G provides appropriate primitives for representing spatial data, supports spatial relationships and allows the specification of spatial integrity rules (topological, semantic and user integrity rules) through its spatial primitives and spatial relationship constructs. Being an object-oriented data model, it also allows some spatial constraints to be encapsulated as methods associated to specific georeferenced classes. Once constraints are explicitly documented in the conceptual modeling phase, and methods to enforce the spatial integrity constraints are defined, the spatial database management system and the application must implement such constraints. This chapter does not cover integrity constraints associated to the representation of simple objects, such as constraints implicit to the geometric description of a polygon. Geometric constraints are related to the implementation, and are covered here in a higher level view, considering only the shape of geographic objects. Consistency rules associated with the representation of spatial objects are discussed in Laurini and Thompson (1992).

Introduction to Database Integrity

Data properties should be seen from the point of view of being as independent as possible from the representation model. In this way, data properties can be analyzed from two different perspectives: from the real world and the database world. A real world data property of a given class may be mapped into a different database class of properties due to materialization issues. This depends on the database paradigm and on the adhesion of the DBMS to that paradigm.

Integrity Maintenance In Extensible Databases

The use of databases for advanced applications is a rapidly growing and changing field, due to the continuous incorporation of new technologies and media in current systems. Whereas in the near past Database Management Systems (DBMS) mainly use to store and manage tabular data, now they need to model complex structured objects, multimedia data, semi-structured and unstructured documents. Each of these improvements has its own semantics and complexity. In order to allow an adequate description of database applications, data models are used to describe the conceptual schema of the database. If new categories of applications need to be incorporated or created, and the data model does not fit well with these applications, the model itself must be expanded. The semantics of the new constructs must be defined and the integrity of objects in the new constructs must be guaranteed.

Database Integrity

In Part I, this chapter surveys the state of the art of the semantic integrity constraints in some relational and object relational available database systems. In Part II, it also provides an overview of the SQL standard integrity issues and describes semantic integrity support in the following DBMSs: Oracle, IBM DB2, Informix, Sybase and PostgreSQL. The major differences and similarities among these systems are analyzed in relation to the definition, semantics and fidelity to the SQL standard prescriptions.

Functional Dependencies For Value Based Identification In Object-Oriented Databases

The Entity-Relationship (ER) model (Chen, 1976) is frequently used for the specification of conceptual database schemas. Entity types and relationship types are the building blocks provided by this data model. A major objective of conceptual database design (see e.g. Batini, Ceri, & Navathe, 1992) is to define entity types and relationship types in such a way that they represent meaningful units of information with respect to the semantics of the modeled application domain. Object types in object-oriented data models are comparable to entity types as far as structural aspects are concerned. However, the ER model explicitly supports relationship types, whereas different approaches are found in object-oriented data models: On the one hand, relationship types may be represented by reference attributes, which means that they are part of the object type itself. This approach, for example, is often found in programming languages. On the other hand, they may be represented explicitly by means of a separate concept as in the ER model. In the latter case there is a close resemblance between entity types and object types. Object types represent sets of objects which are of relevance in the application domain, while relationship types represent relationships between objects.

Consistent Queries Over Databases with Integrity Constraints

Integrity constraints represent an important source of information about the real world. They are usually used to define constraints on data (functional dependencies, inclusion dependencies, etc.). Nowadays integrity constraints have a wide applicability in several contexts such as semantic query optimization, cooperative query answering, database integration and view update. Often databases may be inconsistent with respect to integrity constraints, that is, one or more integrity constraints are not satisfied. This may happen, for instance, when the database is obtained from the integration of different information sources. The integration of knowledge from multiple sources is an important aspect in several areas such as data warehousing, database integration, automated reasoning systems and active reactive databases.