A pictorial query language for querying geographic databases using positional and OLAP operators
Elaheh Pourabbas, Maurizio Rafanelli · ACM SIGMOD Record · 2002
The authors propose a declarative Pictorial Query Language (called PQL) that is able to express queries on an Object-Oriented geographic database drawing the features which form the query. These features refer to the classic ones of a geographic environment (geo-null, geo-points, geo-polyline, and geo-region) and define the alphabet of the above mentioned language. This language, extended with respect to a previous one, considers twelve positional operators and a set of their specifications. Moreover, the possibility to use the mentioned language to query multidimensional databases is discussed. Finally, the characteristic of the mentioned language by a query example is shown.