Pasta-3's graphical query language: direct manipulation cooperative queries, full expressive power
Marthe Kuntz, Rainer Melchert · Very Large Data Bases · 1989
Graphical Direct Manipulation (GrDM) query languages are characterized and positioned with respect to traditional textual query languages. After a brief survey of the current state of the art, the Pasta-3 GrDM query language is presented, with emphasis on three features that make significant new contributions to this field: (1) its GrDM basis (query editing through clicking and dragging of an iconic representation of the query expression), (2) its cooperative environment (handy values, automatic path completion, edit-and-reevaluate loop), and (3) its expressive power (arbitrarily complex conditions, recursive queries, logical variables and quantification, subqueries, mixing in Prolog code). Several examples taken directly from the nearly complete implementation are discussed in detail.