Complex databases can be understood well with visual representation. A graph is a very intuitive and rational structure to visually represent such databases. Graph Data Model (GDM) proposed by the author formalizes data representation and operations on the data in terms of the graph concept. The GDM is an extension of the relational model toward structural representation. In this model, a database is defined by a schema graph where nodes represent record types and arcs represent link types that are relationships between two record types. The capabilities of the GDM include direct...