A query language for XML

TLDR

XML is widely used for electronic data interchange, and as its use expands, applications must integrate, aggregate, clean, and transform data—tasks traditionally addressed by database query languages. The authors introduce XML‑QL, a query language designed to support data extraction, transformation, and integration for XML. XML‑QL is a declarative, relational‑complete language that is simple enough to be optimized. XML‑QL enables extraction from existing XML documents and construction of new XML documents.

Abstract

An important application of XML is the interchange of electronic data (EDI) between multiple data sources on the Web. As XML data proliferates on the Web, applications will need to integrate and aggregate data from multiple source and clean and transform data to facilitate exchange. Data extraction, conversion, transformation, and integration are all well-understood database problems, and their solutions rely on a query language. We present a query language for XML, called XML-QL, which we argue is suitable for performing the above tasks. XML-QL is a declarative, `relational complete' query language and is simple enough that it can be optimized. XML-QL can extract data from existing XML documents and construct new XML documents.