VQL(ID:5560/vql001)Visual Query Language For Uniform Database Access References: concepts of windows and example elements. It utilizes the "restricted universal quantifier " operator in a flexible manner to express or simulate various fundamental queries. It facilitates querying databases of several models in a uniform and consistent way. We demonstrate the capabilities of the language through a rich collection of examples for relational, nested and object-oriented databases and study the formal properties of the relational and nested components. We review related work in the area of visual query languages and discuss various languages in detail. We compare and contrast the properties of these and some popular, commercially available visual query languages with VQL. Finally, we discuss certain implementation considerations and possible extensions to the language. |