초록 ▼

A database query system includes a query assistant that permits the user to enter only queries that are both syntactically and semantically valid (and that can be processed by an SQL generator to produce semantically valid SQL). Through the use of dialog boxes, a user enters a query in an intermedia

A database query system includes a query assistant that permits the user to enter only queries that are both syntactically and semantically valid (and that can be processed by an SQL generator to produce semantically valid SQL). Through the use of dialog boxes, a user enters a query in an intermediate English-like language which is easily understood by the user. A query expert system monitors the query as it is being built, and using information about the structure of the database, it prevents the user from building semantically incorrect queries by disallowing choices in the dialog boxes which would create incorrect queries. An SQL generator is also provided which uses a set of transformations and pattern substitutions to convert the intermediate language into a syntactically and semantically correct SQL query. The intermediate language can represent complex SQL queries while at the same time being easy to understand. The intermediate language is also designed to be easily converted into SQL queries. In addition to the query assistant and the SQL generator, an administrative facility is provided which allows an administrator to add a conceptual layer to the underlying database making it easier for the user to query the database. This conceptual layer may contain alternate names for columns and tables, paths specifying standard and complex joins, definitions for virtual tables and columns, and limitations on user access.

대표청구항 ▼

[ What is claimed is:] [1.] A database query system for interactively creating, with a user, a syntactically and semantically correct query for a relational database having a plurality of tables, each of said tables having a plurality of columns and having a predetermined relationship to another of

[ What is claimed is:] [1.] A database query system for interactively creating, with a user, a syntactically and semantically correct query for a relational database having a plurality of tables, each of said tables having a plurality of columns and having a predetermined relationship to another of said tables, said system comprising:a conceptual layer manager storing conceptual information about the relational database, said conceptual information including structural information concerning the identity of each of the tables and columns and the directionality and cardinality of the relationships between the tables;a query assistant user interface ("QAUI") presenting to the user a selectable table set of selectable tables from among the tables in the database, a selectable column set of selectable columns from among the columns of each of said tables in the database, and a selectable column operations set of selectable column operations on the columns, from which the user may select tables, columns, and column operations to construct a database query for said database, said QAUI further accepting from the user selections of tables, columns, and column operations;a query assistant expert ("QAES") coupled to said QAUI to receive from said QAUI the identity of each table, column, or column operation selected by the user, said QAES returning to the QAUI after each selection by the user an updated version of said selectable table set, said selectable column set, and said selectable column operations set, said QAES excluding from said selectable sets any table, column, or column operation which, if selected by the user, would, based on the then-current state of the database query and said conceptual information, produce a semantically incorrect query.