Querying XML Data

The XML (eXtensible Mark-up Language), proposed by the W3C (World Wide Web Consortium) as the new standard for the data representation and permute in the Internet, is a document mark-up (meta) language adequate to the WWW requisites. With the proliferation of XML documents in the Web, there is a need to store and query them efficiently. In this article we intend to analyse the main characteristics of some of the query languages for XML, coming whether from the Database community, whether from the Internet community, namely the XML-QL, the XQL, the Quilt, as well as the Xquery. This last one is proposed by the W3C Query Working Group with the intent of providing a standard for a XML query language.