Graphical query formulation for an entity-relationship model

Visual query languages for entity relationship model databases

“…However, objective studies are needed, since 'the specific advantages and disadvantages of the various visual approaches for querying ER databases will become apparent only after running carefully designed experiments involving the intended users of the visual interfaces' as [29, p. 244]. Empirical studies can also provide methods to assist an end-user [22].…”

Querying Heterogeneous XML Sources through a Conceptual Schema

“…The target language XPath 1.0 is based on the concept of path expression for navigating through the hierarchical relationships of an XML instance. Thus, we have chosen for the conceptual level a language that is also based on the concept of path expression, and discarded languages like entity-relationship algebras [8,9] and SQL [10] that are based on the join operation.…”

On graph based interaction for semantic query languages

“…Perhaps the above problems have led to the development of view-based semantic query languages in which reflexive relationships are not allowed (see, e.g., [26,5,7]). …”

“…Through this second mechanism the expressive power of the graphical query language reaches the one of the conjunctive queries [8]. To specify a set of adjacent concepts can be seen as the basic building block of the user interaction in building a query, and the way in which the user is allowed to do that in the proposals available in the existing proposals can be reduced to two main paradigms of interaction: path-based (see for instance, [14,13,15,19,20,2]) or view-based (see for instance, [26,5,11,18,12,16,7]). …”

“…Recently, a noticeable effort has been spent in the definition and the experimentation of semantic query languages, ranging on a wide variety of data models and on different query language expressiveness (see, e.g., [14,5,4,10,2,16]). All of the available proposals adopt one between two opposite strategies.…”