Deriving Consistency-preserving Transaction Specifications for (View-)Updates in Relational Databases

We propose a new method for generating transaction specifications for (view-)updates in relational databases that are guaranteed to preserve integrity constraints. The method augments the relational database with a set of transition and events rules, which explicitly define the insertions and deletions induced by a database update. At database design time, an extension of the SLDNF procedure can use these rules as input clauses to produce transaction specifications for compile-time base or view updates. This is done in such a way that the database will never be taken into an inconsistent state, if run-time updates are only effected through the instantiation of the previously obtained transaction specifications. The method draws from previous work of our group in the more general setting of deductive databases, particularly in view updating and integrity constraint checking. KEYWORDS Relational databases, Transaction synthesis, View updating, Integrity checking, Integrity enforcement ..

On the Formal Specification and Derivation of Relational Database Applications

The development of database applications is usually carried out informally. The derivation of database programs directly from formal specifications is a well known and unsolved problem. Most of the previous work in the area either tried to solve the problem too generally or was restricted to some trivial aspects, for example deriving the database structure and/or simple operations. This thesis describes an extension to the traditional database design process aimed at formalizing the development of (relational) database applications. Specifically, it gives a complete description of a general method for the specification of relational database applications using Z, as well as a comprehensive description of a set of rules on how to derive database programs from specifications which result from using the method. The method prescribes how to specify all the important aspects of relational database applications, which includes the definition of relations, the specification of constraints, and querying and updating of relations, including error handling. It also addresses more advanced features such as transactions, sorting of results, aggregate functions, etc. However difficult in general, deriving relational database applications directly from Z specifications written according to the method is not arduous. With appropriate tool support, writing formal specifications according to the method and deriving the corresponding relational database programs can be straightforward. Moreover, it should produce code which is standardized and thus easier to understand and maintain. An intrinsic part of the thesis is a prototype which was built to support the method. It provides a syntactic editor for the method and partially implements the mapping for a specific Relational Database Management System (RDBMS), namely the DBPL system