A TEMPORAL QUERY LANGUAGE-BASED ON CONCEPTUAL ENTITIES AND ROLES

In our previous work [EIEK90], we introduced a Semantic Temporal model based on the Extended Entity-Relationship model (STEER), where we proposed new classification concepts for temporal/conceptual objects and relationships. We defined temporal constraints and outlined rules for preserving temporal integrity constraints. In this paper, we propose a temporal query language based on the STEER data model. The query language is a temporal extension of GORDAS [ElWi81, ElWu90], which is a formal, high-level, user-friendly query language for the Extended Entity-Relationship model. The temporal query language derives its power and flexibility from the distinction between temporal and conceptual objects, and from temporal and conceptual relationships. It provides natural and high level temporal element constructor operators that simplify temporal query expressions.