XML-SQL: An XML Query Language Based on SQL and Path Tables

The goal of this paper is to propose a method in which relational database system is used to process queries on semistructured data. The method uses a combination of relational and semistructured techniques to process XML documents. First, the document is entirely stored within the relational system. Next, an SQL query is evaluated over the relational data representing XML document. Finally, the resulting XML document is constructed which, in turn, can be represented in the standard way within relational database system (by means of an edge table). The proposed method is presented as the XML-SQL language. The language is described formally and by a number of examples. Some implementation solutions are described.