Abstract :
CASE tools inevitably require query and report generation facilities on data held in the SEE repository. The speed and ease of a powerful query language significantly improves productivity in the development of such tools. In the case of relational database management systems, the query language is usually some dialect of SQL. For SEEs based on the International Standard for SEE repositories, PCTE, there is no established query language. This is because the PCTE Object Base is founded on the Entity-Relationship-Attribute (ERA) model, for which “pure” SQL is inappropriate. This paper introduces two navigation-oriented query languages for ERA databases, the first based on PCTE pathnames, and a second, still largely navigation-oriented, much closer to SQL with features in common with the object-oriented query language OQL. Desirable features of such query languages are illustrated and some observations made on query language standardisation
