Michael L. Brodie

On the Design and Specification of Database Transactions

A complete design and specification of database transactions must include both structural and behavioural properties. Structure deals with states and static properties while behaviour concerns state transitions and dynamic properties. Database design techniques emphasize the importance of behaviour but seldom provide for modelling and integrating behaviour and structure.

Data quality in information systems

Abstract Until recently, data quality was poorly understood and seldom achieved, yet it is essential to the effective use of information systems. This paper discusses the nature and importance of data quality. The role of data quality is placed in the life cycle framework. Many new concepts, tools and techniques from both programming languages and database management systems are presented and related to data quality. In particular, the concept of a database constraint is considered in detail. Some current limitations and research directions are proposed.

The application of data types to database semantic integrity

Abstract Data type concepts are used to investigate the extent to which database semantic integrity can be defined and ensured through database structures. Database and datatype concepts are extended mutually to improve the semantic capabilities of both database models and data type systems and to resolve apparent discrepencies between databases and programming languages. To meet database needs, data structuring is developed to form an algebra of data types. A semantically rich database model is used to show that database models can be expressed in terms of data types. Finally, a schema specification language is presented to demonstrate the power of data type tools for the definition of database schemas and for the maintenance of database semantic integrity.

Axiomatic definitions for data model semantics

Abstract The axiomatic method, a widely accepted technique for the precise (formal) definition of programming language semantics, is used to define data model semantics. First, a definition of the term “data model” is developed. The strong relationship between database and programming language concepts is discussed. The nature of data model formalization is described. Based on the experience in programming languages, it is argued that the formal definition of a data model aids database design, database management system implementation, semantic integrity verification and validation, and data model theory. It is further argued that precision must be weighed against understandability, and that a degree of informality can be introduced without loss of precision. Several different formal description techniques and their particular advantages are mentioned. It is argued that in order to achieve desired goals, more than one technique be used to develop consistent and complementary formal definitions of a data model. The axiomatic method is described. Axiomatic definitions are particularly appropriate for the design, analysis, and comparison of schemas, transactions, and databases. The axiomatic definition technique is demonstrated in an annotated, precise definition of the semantics of the structural aspects of a semantic data model which is based on the relational data model.

Data abstraction for designing database-intensive applications

There is a growing exchange of ideas amongst Artificial Intelligence (AI), Database (DB) and Programming Language (PL) researchers concerning conceptual modelling of complex, object-oriented applications. The complexity of these applications arises from complicated structural and behavioral properties which change through time; concurrent, interactive access by users with different processing needs over a shared database; information locality (i.e., DB views, PL data abstractions, AI perspectives); and primarily update-oriented transactions. Two main problems raised by these applications are: managing the intellectual complexity of their design, development and evolution, and defining and ensuring semantic integrity.

Action and transaction skeletons:: High level language constructs for database transactions

The relational data model (RDM) provides a powerful basis for high level language constructs that are used in representing structural (static) and behavioural (dynamic) properties of data intensive applications. A fundamental class of semantic integrity constraints, called interrelational constraints, cannot adequately be represented by structural or behavioural constructs alone. The required structural concept is provided directly by the RDM, but a complementary behavioural concept must be added. The language design issues concern a behavioural concept, called an action skeleton, and its integration with the structural concept. An action skeleton enforces a disciplined design and implementation of database transactions that maintain interrelational constraints. Another design issue concerns the use of syntax to constrain design and implementation choices.