A graphical calculus-based query language is defined for a newnsemantic data model. The semantic data model supports participationnconstraints on relationship sets, and the query language takes advantagenof these participation constraints to provide a new way to pose queries.nIn particular, it is shown how participation constraints lead to annelegant formulation of universal-quantification queries. Participationnconstraints also lead to an elegant formulation of queries that requirencounting. Examples are provided of several queries that are eitherndifficult or impossible to pose in standard query languages, but arenstraightforward in the proposed calculus-based query language
展开▼
