A knowledge-based database assistant, KDA, is described that has a query-guide function, an SQL-like database query generator, and an interface for subset-English. KDA can be used to design the front end of an SQL database system or a computer-based SQL tutorial system. A method is discussed for transforming a semantic network representing a user's conceptual query into one providing the information required by the system to respond to a query. The query pattern is an expression in natural language representing the semantic structure of concepts. The user expresses queries by filling parentheses in the query patterns with appropriate words. The query-pattern instances thus obtained are then translated into SQL-like relational database queries. The translation is carried out by evaluating operations defined on a semantic network named G-Net which conveys knowledge about application fields, the database schema, and the syntax of SQL.
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