XML Query Language (XQL) is a programming language that can be used to query documents in databases
. Similar to Structured Query Language (SQL) for relational databases, XQL is used to retrieve XML documents or parts of documents from an XML data source. The command set of XQL is similar to the XSL pattern language, Extensible Stylesheet Language (XSL), which can be used to extract specific elements from a document. In addition, XQL provides the possibility to relate foreign documents to each other.