GRAQULA: A graphical query language for entity-relationship or relational databases

GRAQULA is a graphical language for querying and updating a database. One version of GRAQULA provides a user interface for the entity-relationship data model, and another version (with almost identical syntax) provides a user interface for the relational model. Each version is relationally complete, and each depicts relationships (or expected joins) graphically, GRAQULA provides logical operations (e.g. negation) on graphical objects; these operations have user-specified scopes, allow nesting, and can involve existential or universal quantification. Aggregates (e.g. average) also have user-specified scopes. Queries can invoke other queries, and users and queries can pass parameters to queries. The design reflects a specified set of goals, including expressive power, consistency, and limitation of required memorization. © 1993.