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 forclauses and object-correlation, thus avoiding the need to deal explicitly with implementation details such as relational tables, null values, outer joins, groupby 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