A graphical query language for the Binary Relationship Model

摘要

We present a graphical query language for the Binary Relationship Model. The language is closed with respect to the model, and it supports queries as well as view definitions.The user interacts with the database using a mouse on a graphical representation of the database schema. He first specifies a query context graph by highlighting parts of the database schema. A query context graph is an unordered graph that defines the context for the evaluation of a subsequent set of queries and view definitions. A query identifies the object type which is the subject of the query and specifies a set of conditions on the query context graph. The object type and the conditions constitute the minimum of information needed to traverse the query context graph and evaluate the query. The result of a query is the set of elements of the identified object type that are related to elements in the query context graph in accordance with the specified conditions.The language is one of several tools for the Binary Relationship Model being implemented by the Database Systems Group at Maryland.