The authors describe “gql/ER,” a graphics-based, query system for extracting information from databases. They first provide guidelines for the useful capabilities/properties of a database query interface: (1) navigation aids, (2) graphics, (3) browsing, (4) conciseness, and (5) a high level data model.

The gql/ER system presented is a menu-based, mouse-driven graphic system which displays, edits, and translates Entity-Relationship (E-R) diagrams of E-R database schemas. The system has been partially implemented (in C using the GPAC graphics package) on a PDP 11/45 under UNIX. In the current implementation E-R queries are translated by gql/ER into relational queries in the query language of the relational database management system, Mistress.

The authors show in screen session examples how to manipulate the relationships of database entities by manipulating graphical symbols and connectors between them. They describe automatic and manual modes of associating a relational algebra expression with a query (only manual mode has been implemented so far).

The graphical user interface examples in the paper are typical of the trend in the personal and professional computer worlds to remove the user from procedural responsibilities and to develop natural ways to conceptualize and abstract the data and processes which software systems manipulate.