L. Mohan et Rl. Kashyap, A VISUAL QUERY LANGUAGE FOR GRAPHICAL INTERACTION WITH SCHEMA-INTENSIVE DATABASES, IEEE transactions on knowledge and data engineering, 5(5), 1993, pp. 843-858
Citations number
51
Categorie Soggetti
Information Science & Library Science","Computer Sciences, Special Topics","Computer Applications & Cybernetics
This paper presents a visual query language called VQL for interacting
with an object-oriented schema-intensive data model. VQL allows conve
nient access to the various types of knowledge captured by the semanti
c model. It consists of a set of ''graphical primitives'' along with a
combination grammar for creating graphical queries. The visual langua
ge is internally supported by a prolog-like predicate based query lang
uage. The formal grammar underlying the predicate based language is al
so presented. Apart from being able to create simple queries that can
be specified in SQL or QBE, VQL can be used for making queries on any
object-oriented data model including the generalization of the E-R mod
el. VQL also handles complicated, indirect queries, specially those th
at require a reasoning system for query interpretation and response ge
neration. Further, recursive queries on graph structures such as findi
ng transitive closures of graphs may be easily specified. Perhaps the
most powerful feature of VQL is its ability to provide high semantic e
xpressibility (in being able to specify highly complex queries) while
maintaining simplicity in the user's query formulation process. VQL is
embedded in an object-oriented graphical database interaction environ
ment that supports schema creation and manipulation in addition to dat
abase querying and updation. The prototype has been implemented in Sma
lltalk-80 running on a Sun 3/60 workstation. All the illustrations of
visual interaction presented in this paper are taken from actual inter
action sessions.