Kaleidoscope: a cooperative menu-guided query interface (SQL version)

Kaleidoscope is presented for the problem of providing cooperative interfaces for database users. The system proposes valid query constituents step-by-step and provides lexical and semantic feedback immediately to users. To implement this intraquery guidance, the context-free grammar (CFG) is extended with context variables and several types of procedural decorations and the knowledge useful for pruning nonsensical queries and providing semantic feedback is articulated. For the structured query language (SQL) interface, this knowledge includes a strong domain concept, functional dependence and integrity-constraint rules. The same types of knowledge are useful both for postquery cooperation and intraquery guidance. However, Kaleidoscope more actively utilizes such knowledge under the belief that a system knowledgeable enough to correct or to suggest the postquery correction of failed queries should use its knowledge first to guide users away from query failure. A query language whose syntax and semantics closely follow those of the English language is being developed. With this language, it is expected that Kaleidoscope will serve a wider range of users