Conceptual Queries Using ConQuer-II

Formulating non-trivial queries in relational languages such as SQL and QBE can prove daunting to end users. ConQuer is a conceptual query language that allows users to formulate queries naturally in terms of elementary relationships, operators such as “and”, “or”, “not” and “maybe”, contextual for-clauses and object-correlation, thus avoiding the need to deal explicitly with implementation details such as relational tables, null values, outer joins, group-by clauses and correlated subqueries. While most conceptual query languages are based on the Entity-Relationship approach, ConQuer is based on Object-Role Modeling (ORM), which exposes semantic domains as conceptual object types, allowing queries to be formulated via paths through the information space. As a result of experience with the first implementation of ConQuer, the language has been substantially revised and extended to become ConQuer–II, and a new tool, ActiveQuery, has been developed with an improved interface. ConQuer-II’s new features such as arbitrary correlation and subtyping enable it to be used for a wide range of advanced conceptual queries.